Guy Holt

No, I don’t know of a LED Fixture using Phosphor White LEDs that is able to render color accurately. The problem is that, given the discontinuous nature of their spectral output, they simply are not capable of rendering colors accurately – that includes the Litepanels. If you compare the spectral power distribution graphs of LEDs below to that of a Tungsten source you can see why. A spectral power distribution of a lamp indicates how much energy is present in each part of the spectrum. As you can see above, Tungsten lamps have a continuous spectrum. Given how they produce white light, even high CRI Phosphor White LEDS have a discontinuous spectral quality that is unlike that of Tungsten lights. In the case of the 3200K Phosphor White LEDs above, the phosphors added shape the spectral distribution by enhancing certain colors in the spectrum to simulate the spectral distribution of incandescent light. As a result, the spectral distribution of Phosphor White LEDs resembles a series of peaks and valleys. There is a big spike at about 465nm (the blue LED) and a broader bump between 500 and 700nm produced by the phosphors. Even though the spectral power distribution has these peaks and valleys, the human eye perceives the light as white light. While the discontinuous spectral distribution of high CRI Phosphor White LEDS may appear white to the eye, and the color of objects illuminated by it appear natural to the eye, to film emulsions and digital imaging systems designed to reproduce accurate color under continuous spectrum light sources (like daylight or incandescent lamps), the color of the same objects will appear unnatural on screen (as the illustrations below make clear.) That is, the hue of an object being illuminated by this "white light" can be drastically different than expected when it appears on the screen. For example, below is a "Macbeth chart" contrasting the resulting effect upon different color swatches of studio tungsten light and a representative high CRI Phosphor White LED lighting instrument. Split Macbeth chart: each color patch shows the visible effects of studio tungsten light in the top half of the patch, and a representative Phosphor White LED lighting instrument in the bottom half. A common test chart used for assessing color performance of motion picture imaging systems, the chart above would be more accurately called a "split Macbeth chart" because each color patch shows the visible effects of the two light sources; studio tungsten in the top half of the patch, and the Phosphor White LED instrument in the bottom half. Although your computer display is not likely to be a calibrated reference monitor, the wide variations in color patch hue caused by the discontinuous spectral distribution of the Phosphor White LED should be readily apparent. What accounts for these results? First, as you can see from its' spectral power distribution above, Phosphor White LEDS, compared to continuous light sources, have no output at wavelengths shorter than about 425nm, which means that violet colors don't render well. Second, there is minimal output in the medium blue-cyan-turquoise range from about 465-510nm, which is why the aqua-type colors don't render well either. Third, with the long-wavelengths cutoff in the high-600 nm range, pinks, reds, oranges, and other long wave-length colors tend to look a little dull under Phosphor White LEDs, compared with how they look under continuous spectrum light sources (daylight, HMI, Tungsten) which extend all the way out on the long-wavelength end. Lacking these long wavelength colors within the spectrum, skin tones tend to look a little pale. Finally, as you can see from the gray scale at the bottom, this particular Phosphor White LED Luminary has an overall magenta bias. While you can white balance out/time out this magenta bias in digital video cameras/digital film intermediate, the camera/timer is not able to replace the parts of the spectrum that are missing all together. And since gels only rebalance the spectral distribution of a light source by passing the wavelength of the color that they are, gels cannot correct for these deficiencies because there is not much light of those wavelengths to pass in Phosphor White LEDs to begin with. Left: Tungsten source, Right: White Phosphor LED source. This inability of Phosphor White LEDs to render color accurately is very visible in tests recently performed by The Academy of Motion Picture Arts and Sciences (AMPAS) as part of their “Solid State Lighting Project Technical Assessment.” (see http://www.screenlightandgrip.com/html/emailnewsletter_generators.html#anchorHigh%20Output%20AC%20LEDs for details.) In one (above) a model was photographed wearing a dress that had a number of different blue tints. Footage was shot with both a true tungsten source and a White Phosphor LED source. The tungsten-lit footage displayed all of the subtle differences in blue tones in the fabric, while the LED-lit footage, lacking cyan output, showed just a nice blue dress, without the same richness of hue. Since the light doesn’t put out much cyan, the camera/film simply can’t record it. The same holds true of flesh tones illuminated by LED light. As is also evident in the pictures above, skin tones don’t reproduce well under LED lights because of the steep drop off of high frequency colors (above the 600nm cut off) such as pinks, reds, oranges, and other long wave-length colors. As the illustration below, comparing the reflected spectral distribution of a Caucasian skin tone under theoretical pure white light (an even distribution of all wavelengths) to that of a Phosphor White LED demonstrates, absent these wavelengths the skin tones look pale under LEDs because light reflected by the skin tone is likewise absent these critical long wavelength colors. Reflected Spectral Distribution of Caucasian skin tone under theoretical White Light and Phosphor White LED Light In the picture above illuminated by the Phosphor White LED, both the cyan/blue dress and the skin tone, don’t reproduce well because you can't get accurate color reflected from an object unless that color is in the light in the first place. In other words, if the light source doesn’t generate the color (cyan), it is not reflected by the object (the dress) and so the camera/film simply can’t record it. And, as Cinematographer Daryn Okada, ASC, discovered the hard way, color gel packs, camera white balance, or digital intermediate timing can’t bring it out if it isn’t there to begin with. Like many of us, Daryn Okada uses LEDs as “touch up” lights to add a little something where key lights don’t cover. Needing to touch up a face on one talent mark, he once hid a small LED unit behind a chair, to add some glow to an actress’s face when she reached a mark where the keys had fallen off. “The manufacturer claimed the unit to be a ‘tungsten LED source’” he recounts. “She stopped right in the doorway, where I had this LED, and looked fine. But when I got the dailies back, her face was totally magenta.”; What’s worse, Okada says the image could not be repaired in post, because there wasn’t enough of the right color of light in the scanned negative for a color timer to bring out. This is a good example of the fact that, the bottom line is that, simply by nature of their discontinuous spectral distribution, even high CRI Phosphor White LEDs will never accurately reproduce colors on screen regardless what can be done in post. To make matters worse, common color meters, like the Minolta III F, are completely useless with LEDs in determining what gels to use. The meter makes its calculation of the color temperature based on an assumption that the light source has a continuous spectrum. Color readings of an LED have been shown to be misleading for both correlated color temperature and green/magenta shift. And, manufacturer’s CRI ratings are not necessarily the best indicator to judge the color rendering capability of LED fixtures because it is a measurement that can be messaged by manufacturers to give high readings without giving good results. You have to be wary of all the claims made by LED head manufacturers. Whenever a new lighting technology comes on the market, the manufacturers put a little spin on the scientific data which has a tendency to cloud issues. For this reason, to pick the right LED luminary for a particular job it helps to have a thorough understanding of the technology. For our company newsletter I have put together an overview of the technology and what LED products are available for motion picture lighting (available at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html#anchorHigh%20Output%20AC%20LEDs.) Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental and Sales in Boston

No relation as far as I know. - Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental & Sales in Boston

If you compare the spectral power distribution graphs (below) of natural daylight and LEP lamps you see that, except for very brief drop outs at approximately 410 nm and again at 451 nm, the light output of LEP lamps is almost identical to natural daylight and so will in fact mix easily with other daylight sources like HMIs, Daylight Kinos, and natural daylight. And, as also can be seen in their spectral distribution graphs above, Plasma lamps have a much more continuous color spectrum than even the best LED luminaries on the market today. It is LEDs that don’t mix well with other sources. LEDs are so deficit in certain parts of the color spectrum that by the time you come up with a color gel pack to match them to a continuous light source like a tungsten or HMI light, the LED panel would put out very little light with all the gels on it. 3200K Phosphor White LEDs, in particular, don’t mix well with Tungsten sources. As you can see from the spectral power distribution graphs below, the spectral distribution of even high CRI Phospher White LEDs, like the Litepanels and Mole, are very dissimilar to that of Tungsten sources. A spectral power distribution graph of a lamp indicates how much energy is present in each part of the spectrum. In the case of the 3200K Phosphor White LED above, the phosphors added shape the spectral distribution by enhancing certain colors in the spectrum to simulate the spectral distribution of incandescent light. As a result, the spectral distribution of Phosphor White LEDs resembles a series of peaks and valleys with a big spike at about 465nm (the blue LED) and a broader bump between 500 and 700nm produced by the phosphors. Even though the spectral power distribution has these peaks and valleys, the human eye perceives the light as white light. While the discontinuous spectral distribution of high CRI White Phosphor LEDS (far left) may appear white to the eye, and the color of objects illuminated by it appear natural to the eye, to film emulsions and digital imaging systems designed to reproduce accurate color under the continuous spectrum of Tungsten lamps, the color of the same objects will appear unnatural on screen as the illustrations below make clear. That is, the hue of an object being illuminated by this "apparent white light" can be drastically different than expected when it appears on the screen. For example, below is a "Macbeth chart" contrasting the resulting effect upon different color swatches of studio Tungsten light and a representative high CRI 3200K Phosphor White LED lighting instrument (that shall remain nameless.) Split Macbeth chart: each color patch shows the visible effects of studio tungsten light in the top half of the patch, and a representative Phosphor White LED lighting instrument in the bottom half. A common test chart used for assessing color performance of motion picture imaging systems, the chart above would be more accurately called a "split Macbeth chart" because each color patch shows the visible effects of the two light sources – Tungsten in the top half of the patch, and the Phosphor White LED lighting instrument in the bottom half. Although your computer display is not likely to be a calibrated reference monitor, the wide variations in color patch hue caused by the discontinuous spectral distribution of the Phosphor White LED lighting instrument should be readily apparent. What accounts for these results? First, as you can see from its' spectral power distribution above, Phosphor White LEDS, compared to the continuous light output of Tungsten lamps, have no output at wavelengths shorter than about 425nm, which means that violet colors don't render well. Second, there is minimal output in the medium blue-cyan-turquoise range from about 465-510nm, which is why the aqua-type colors don't render well either. Lacking these complementary colors within the spectrum, skin tones and warm, amber-yellow colors don't stand out. Third, with the long-wavelengths cutoff in the high-600 nm range, pinks, reds, oranges, and other long wave-length colors tend to look a little dull under Phosphor White LEDs, compared with how they look under the continuous spectrum light of Tungsten filaments which extend all the way out on the long-wavelength end. Finally, as you can see from the gray scale at the bottom, this particular Phosphor White LED Luminary has an overall magenta bias. While you can white balance out/time out this magenta bias in digital video cameras/digital film intermediate if the scene is uniformly lit with the same LEDs, the camera/timer is not able to replace the parts of the spectrum that are missing all together. And since gels only rebalance the spectral distribution of a light source by passing the wavelength of the color that they are, gels cannot correct for these deficiencies because there is not light of those wavelengths to pass in White Phosphor LEDs to begin with. Left: Tungsten source, Right: White Phosphor LED source. This inability of LEDs to render color is very visible in tests recently performed by The Academy of Motion Picture Arts and Sciences (AMPAS) as part of their “Solid State Lighting Project Technical Assessment.” (see http://www.screenlightandgrip.com/html/emailnewsletter_generators.html#anchorHigh%20Output%20AC%20LEDs for details.) In one (above) a model was photographed wearing a dress that had a number of different blue tints. Footage was shot with both a true tungsten source and a White Phosphor LED source. The tungsten-lit footage displayed all of the subtle differences in blue tones in the fabric, while the LED-lit footage, lacking cyan output, showed just a nice blue dress, without the same richness of hue. You can also see above that, absent cyan, the skin tones don’t stand out because that complementary color (cyan) within the spectrum is not present. Since the light doesn’t put out much cyan, the camera/film simply can’t record it. And, as Cinematographer Daryn Okada, ASC, discovered the hard way, color gel packs, camera white balance, or digital intermediate timing can’t bring it out if it isn’t there to begin with. Like many of us, Daryn Okada uses LEDs as “touch up” lights to add a little something where key lights drop off. Needing to touch up a face on one talent mark, he once hid a small LED unit behind a chair, to add some glow to an actress’s face when she reached a mark where the keys had fallen off. “The manufacturer claimed the unit to be a ‘tungsten LED source,’” he recounts. “She stopped right in the doorway, where I had this LED, and looked fine. But when I got the dailies back, her face was totally magenta.” What’s worse, Okada says the image could not be repaired in post, because there wasn’t enough of the right color of light in the scanned negative for a color timer to bring out. This examples demonstrates that, the bottom line is that, by nature of their discontinuous spectral distribution, even high CRI White Phosphor LEDs won’t mix well with Tungsten sources. Mixed with the uniform continuous light source of a studio lit with tungsten fixtures, the color deficiencies of Phosphor White LEDs will be quite noticeable and unacceptable by comparison. LEP lamps, by comparison, generate light with a continuous color spectrum that is almost an exact match to Daylight (see graphs above.) For instance, LEP lamps, unlike LED lamps, generate light at wavelengths shorter than 425nm. Unlike LED lamps, LEP lamps also output in the medium blue-cyan-turquoise range from about 465-510nm. And, the output of LEP lamps stay strong all the way out on the long-wavelength end, well beyond the 600 nm cutoff where the output of LEDs start to drop off rapidly. Capable of a fuller spectrum colors look more vibrant under LEP light where they tend to look a little dull under LEDs. Plasma lights, as opposed to LEDs, deliver the same output as full-spectrum Daylight or HMI sources. Another reason to stay away from Phosphor White LEDs in mixed light situations is that, as illustrated above, their output depreciates overtime and their color shifts much faster than the manufacturers say. For a detailed analysis of the practical implications of the color output of HMI, LED, and LEP lamps see our newsletter at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html#anchorHigh%20Output%20AC%20LEDs. - Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental and Sales in Boston.

While the restrike times on Plasma lamps is not ideal, they are, in my experience, no different than HMIs. I have never encountered an HMI that was consistently restrikeable. For that reason I always avoid turning them off unless I know there will be several minutes before they will be needed again and I always run out a second head cable if there is any question about the head placement so that it can move without being turned off. Taking similar precautions with LEPs will assure that you are never left waiting for the light to restrike, unless of course there was an unexpected kick out. Freddie, what do you see to be the "colour temp issues?" Please elaborate. - Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental & Sales in Boston

For the record, Jon is co-creator and owner of Hive Lighting. - Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental & Sales in Boston

Ryan, there is a new light technology introduced at NAB this year that you may want to consider because it offers a number of benefits over existing LED, Fluorescent, and HMI technology. It’s called Light Emitting Plasma, or LEP, it is getting a lot of press lately. However, as with any new technology, you have to be wary of all the claims made by the manufacturers. At present there are three motion picture LEP lamp heads on the market: the Photon Beard Nova 270, the Helio 270, and Hive Lighting’s Hornet 180. All three lamp heads use the same Luxim Plasma Emitter behind Fresnel lenses. The Photon Beard Nova 270 and Hive Hornet 180 can be operated on batteries at 28 Volts or off a Universal (90-305Vac, 50/60Hz) AC power supply (the power supply is separate in the case of the Photon Beard Nova 270. The Helio 270, by comparison is a stripped down, more robust location production instrument that offers a built-in 120V/60Hz AC power supply (no DC option) with near unity (.99) Power Factor. As such, the Helio 270 is nearly half the price of the other two heads. For our company newsletter I have put together an overview of the technology and what products are available for motion picture lighting (available at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html#anchorHigh%20Output%20LEPs.) In this newsletter article I have tried to cut through some of the hype. Here is a quick summary of a few of the issues. The Photon Beard Nova 270 (left), a "Hive" of Hornet 180s (center), and the Helio 270 (right.) LEP bulbs are capable of intense light output. One manufacturer, Luxim, claims their technology can produce 144 lumens per watt. In contrast, Tungsten Halogen bulbs produce 15 lumens per watt, LED emitters produce between 65 to 85 lumens per watt (in practical applications), and HMI bulbs produce 90 Lumens per watt. While there is truth in this claim as it pertains to an LEP bulb in isolation, as with LEDs, manufacturers have not realized anything close to that kind of lumen efficiency within the framework of a practical light that will burn in all lamp orientations. The Helio 270 LEP When the pill sized LEP bulb in mounted in the “puck” so that it will burn in all head orientations, the emitting area is no more than 1/4" x ¼." In this configuration, the 273W LEP bulb will deliver 16000 lumens or 57 lumens per watt. While much less than the 37’000 lumens the bulb will generate fully exposed in a horizontal position, it cannot be tilted up in that orientation. On the plus side, mounted so that it will burn in all orientations, all of its’ output is forward directed within a 60 degree angle so it doesn’t require a reflector. Such a highly localized forward directed light is ideal for Fresnel type instruments. As close an approximation to the ideal point source that exists today, its light output favors the central portion of the Fresnel lens. Since, this part of the lens has greater transmittance, LEPs are a more efficient source for Fresnel type heads than tungsten filaments, LED arrays, and even HMI arcs. For this reason you get more of those lumens transmitted through the lens in a highly collimated light that is very clean and crisp making it great for cutting shadows or gobo effects. The 273W LEP bulb in a Fresnel type instrument has an output comparable to a 575W HMI Fresnel. Forward directed output of Helios 270 LEP LEP head manufacturers also claim that LEP lamps provide a CRI of 94+. But, more important than their high CRI ratings, is the fact that LEP lamps generate light with a continuous color spectrum. If you compare the spectral power distribution graphs (below) of natural daylight and LEP lamps (available at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html#anchorHigh%20Output%20LEPs) you see that, except for very brief drop outs at approximately 425 nm and again at 475 nm, the light output of LEP lamps is almost identical to natural daylight. And, as also can be seen in their spectral distribution graphs above, Plasma lamps have a much more continuous color spectrum than even the best LED luminaries on the market today. For instance, LEP lamps, unlike LED lamps, generate light at wavelengths shorter than 425nm - which means that violet colors will render better. And, unlike LED lamps, LEP lamps also output in the medium blue-cyan-turquoise range from about 465-510nm so aqua-type colors render well by comparison. Skin tones and warm, amber-yellow colors stand out better under LEP lamps because of the strong presence of their complementary colors. And, since the output of LEP lamps extend all the way out on the long-wavelength end (well beyond the 600 nm cutoff of LEDs), pinks, reds, oranges, and other long wave-length colors look vibrant under LEP light where they tend to look a little dull under LEDs. As a continuous spectrum source, colors not only appear more natural and vibrant under LEP lamps than under LED lamps, they also reproduce more accurately on the screen since, as is also evident by their spectral distribution graph, the output of LEP lamps is almost an exact match to the spectral sensitivity of daylight film emulsions and digital sensors. Plasma lights will deliver the same true-to-life color rendition previously achievable only with full-spectrum Daylight or HMI sources. Where we are a long way off from having a single-die LED with sufficient output and correlated color temperature to match HMIs, LEP lamps are a cost effective alternative to expensive HMI Fresnel systems when it comes to generating daylight balanced light. This feature of LEPs benefits users of DSLRs and the Red One in particular. One downside to lighting for the 5000K native color balance of CMOS sensors in the past has been that it requires an all 5000K balanced lighting package and HMIs are considerably more expensive to buy or rent than other light sources. Kino Flo fixtures, particularly the Parabeams, are a cost effective alternative to HMIs because they can use either 3200K or 5500K tubes. But, the drawback to fluorescent fixtures (like LED fixtures) is that they generally have a very broad soft light output that drops off rapidly which means the units need to be positioned close to the subject they are lighting. This characteristic has always made them better suited to lighting documentary interviews than dramatic scenes. With a 5300K output comparable to that of a 575 HMI Fresnel, the Helio 270 in particular offers the same benefit of being a less expensive alternative to HMIs, but also offers the added benefit of being more versatile than a Kino Flo or LED fixture. Not only does it offer the capacity of traditional Tungsten/HMI Fresnels to throw and control its light output (making it a more suitable Key and Backlight source for lighting dramatic scenes), but it also has sufficient output to bounce it or waste some output to diffusion material to make it softer (existing LEDs put out barely enough, with none to waste.) It’s capacity to provide both hard crisp light that will throw a distance and is easily controlled, as well as offer soft light with diffusion, makes the Helio 270 much more versatile than any Fluorescent light or LED array presently available. It also offers a number of benefits that the new LED Fresnels and traditional HMI Fresnel do not. For instance, LEPs do not require the active microprocessor color control that is required to assure consistent color rendition in LEDs. Absent such microprocessor based color management systems, LEPs are less expensive and more robust than LED Fresnels. An added benefit to LEPs is that color meters, like the Minolta III F, that make their calculations of the Color Temperature (CT) based on a light sources continuous spectrum, are able to generate accurate reading of the CT and Green/Magenta of LEP lamps. Color meters are completely useless reading the “spiky” discontinuous color spectrum of LEDs (see my newsletter article for details .) The biggest benefit to LEPs in comparison to HMIs has got to be the cost savings in not having to replace lamps every 500 - 750 hrs as is the case with HMIs (or an entire LED light panel when its' emitters reach low light failure.) Where a 575w HMI globe typically retails for approximately $150.00, the 5000 hr L85 lamp life of an LEP bulb is equal to seven HMI globes, which amounts to a savings of $1050.00, or nearly half the cost of the Helio 270 Plasma lamp head. The Helio 270 LEP Plasma emitters use solid state, hardened components that improve their reliability under harsh location production. Plasma bulbs are rugged and vibration resistant, and so unlike HMIs will not break or explode inside expensive heads. Since the LEP emitter is extremely compact, in the case of the Helio 270 at least the emitter, driver, and power supply all fit in the lamp head (the Photon Beard Nova 270 uses a separate AC power supply), eliminating the need for a separate ballast connected by header cables (the acknowledged Achilles heel of HMI systems.) Finally, with much lower UV emissions, LEPs do not require elaborate and ultimately finicky safety switches. In total, LEPs have an order of magnitude better reliability than conventional HMI lamp heads while offering the intense beam and the colorful spectrum needed for motion picture production. Unlike similar sized HMIs, LEP heads use Power Factor Corrected (PFC) power supplies. In fact, we are looking at including the Helio 270 in our HD Plug & Play Pkg. because it has a Power Factor of .99 making it a near linear load. As a result, it uses power more efficiently, minimizes return current, and generates virtually no line noise. Where, it is as much the Harmonic Noise that non-PFC HMI, Fluorescent, and LED power supplies kick back into the power stream, as it is their higher Apparent Power, that limits the total number of them that can be reliably operated on conventional portable generators; the efficiency and near unity Power Factor of this LEP head means that you can operate more of them on portable gas generators. For instance, you can operate four 575W HMIs on a 6500W portable AVR generator, where you should be able to operate 23 of these 270W LEP heads (each with an output comparable to a 575W HMI). Oscilloscope shots comparing the current and voltage waveforms of the PFC Helio 270 with an equivalent wattage of non-PFC LEDs Where LEP is radically new technology there is a lot to get your head around. One way to think of a LEP bulb is as a tiny discharge lamp. But, unlike an HMI bulb it does not have electrodes. Instead of applying a voltage and drawing a current through the lamp to create light as does an HMI, the energy that creates light in an LEP comes via a high frequency RF transmitter. The RF waves heat the materials inside the lamp and bring those materials to a plasma state so that the lamp emits a "flicker-free" light. Besides better color rendering, light quality, and lamp life, this different method of transforming electricity into light has other benefits as well. For more details about LEPs see our newsletter article at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html#anchorHigh%20Output%20LEPs. Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental & Sales in Boston

Once you cut through the hype, the bottom line is that LEP heads offer a number of advantages over LED & HMI technology. Where we are a long way off from having a single-die LED with sufficient output and correlated color temperature to match daylight, LEP lamps are really the only cost effective alternative to expensive HMI Fresnel systems when it comes to generating full spectrum daylight balanced light. This feature of LEPs benefits Red users and DSLR users in particular. One downside to lighting for the 5000K native color balance of CMOS sensors in the past has been that it requires an all 5000K balanced lighting package and HMIs are considerably more expensive to buy or rent than other light sources. Kino Flo fixtures, particularly the Parabeams, are a cost effective alternative to HMIs because they can use either 3200K or 5500K tubes. But, the drawback to fluorescent fixtures (like LED fixtures) is that they generally have a very broad soft light output that drops off rapidly which means the units need to be positioned close to the subject they are lighting. This characteristic has always made them better suited to lighting documentary interviews than dramatic scenes. With a 5300K output comparable to that of a 575 HMI Fresnel, the Helio 270 Plasma lamp in particular offers the same benefit of being a less expensive alternative to HMIs, but also offers the added benefit of being more versatile than a Kino Flo or LED light panel. Not only does it offer the capacity of traditional Tungsten/HMI Fresnels to throw and control its light output (making it a more suitable Key and Backlight source for lighting dramatic scenes), but it also has sufficient output to bounce it or waste some output to diffusion material to make it softer (existing LEDs put out barely enough, with none to waste.) It’s capacity to provide both hard crisp light that will throw a distance and is easily controlled, as well as offer soft light with diffusion, makes the Helio 270 much more versatile than any Fluorescent light or LED array presently available. It also offers a number of benefits that the new LED Fresnels and traditional HMI Fresnel do not. For instance, LEPs do not require the active microprocessor color control that is required to assure consistent color rendition in the best LEDs on the market today. Absent such microprocessor based color management systems, LEPs are less expensive and more robust than LEDs. Plasma lamps also have a much more continuous color spectrum than even the best LED luminaries. As is evident in the Spectral Power Distribution graphs below, LEP lamps, unlike LED lamps, generate light at wavelengths shorter than 425nm - which means that violet colors will render better. And, unlike LED lamps, LEP lamps also output in the medium blue-cyan-turquoise range from about 465-510nm so aqua-type colors render well by comparison. Skin tones and warm, amber-yellow colors stand out better under LEP lamps because of the strong presence of their complementary colors. And, since the output of LEP lamps extend all the way out on the long-wavelength end (well beyond the 600 nm cutoff of LEDs), pinks, reds, oranges, and other long wave-length colors look vibrant under LEP light where they tend to look a little dull under LEDs. As a continuous spectrum source, colors not only appear more natural and vibrant under LEP lamps than under LED lamps, they also reproduce more accurately on the screen since, as is also evident by their spectral distribution graph, the output of LEP lamps is almost an exact match to the spectral sensitivity of daylight film emulsions and digital sensors. An added benefit to LEPs is that color meters, like the Minolta III F, that make their calculations of the Color Temperature (CT) based on a light sources continuous spectrum, are able to generate accurate reading of the CT and Green/Magenta of LEP lamps. Color meters are completely useless reading the “spiky” discontinuous color spectrum of LEDs (see my newsletter article for details .) The biggest benefit to LEPs in comparison to HMIs has got to be the cost savings in not having to replace lamps every 500 - 750 hrs as is the case with HMIs (or an entire LED light panel when its' emitters reach low light failure.) Where a 575w HMI globe typically retails for approximately $150.00, the 5000 hr L85 lamp life of an LEP bulb is equal to seven HMI globes, which amounts to a savings of $1050.00, or nearly half the cost of the Helio 270 Plasma lamp head. The Helio 270 LEP Another advantage is that Plasma emitters use solid state, hardened components that improve their reliability under harsh location production. Plasma bulbs are rugged and vibration resistant, and so will not break or explode inside expensive lighting heads the way HMI bulbs can. Since the LEP emitter is extremely compact, in the case of the Helio 270 at least the emitter, driver, and power supply all fit in the lamp head (the Photon Beard Nova 270 uses a separate AC power supply), eliminating the need for a separate ballast connected by header cables (the acknowledged Achilles heel of HMI systems.) Finally, with much lower UV emissions, LEPs do not require elaborate and ultimately finicky safety switches. In total, LEPs have an order of magnitude better reliability than conventional HMI lamp heads while offering the same intense beam and the colorful spectrum needed for motion picture production. Finally, Power Factor Correction (PFC) is standard in LEP lamp heads where it is not in HMI ballasts. In fact there is one LEP head that we are looking at (not the Photon Beard Nova 270 – it’s too expensive) because it has a Power Factor of .99 making it a near linear load. As a result, it uses power more efficiently, minimizes return current, and generates virtually no line noise. Where, it is as much the Harmonic Noise that non-PFC HMI, Fluorescent, and LED power supplies kick back into the power stream, as it is their higher Apparent Power, that limits the total number of them that can be reliably operated on conventional portable generators; the efficiency and near unity Power Factor of this LEP head means that you can operate more of them on portable gas generators. For instance, you can only safely operate four 575W HMIs on a 6500W portable AVR generator, where you should be able to operate 23 of these 270W LEP heads (each with an output comparable to a 575W HMI). Oscilloscope shots comparing the current and voltage waveforms of the PFC Helio 270 with an equivalent wattage of non-PFC LEDs Besides better color rendering, light quality, and lamp life, this different method of transforming electricity into light has other benefits as well. For more details about LEPs see our newsletter article at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html#anchorHigh%20Output%20LEPs. Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental & Sales in Boston

What is the “lamp life” of an LEP bulb is up for debate. Peter Daffarn of Photo Beard wrote in the Cinematographer’s Mailing List (CML): “Lamp life as quoted by Luxim is 30,000 hours but we are saying 20,000 to be sure.” Such claims of 20'000 – 30’000 hr lamp life made by manufacturers like Photon Beard should be taken, I think, as nothing more than marketing hyperbole. Determining the "life" of an LEP, like that of an LED, is a very complex matter because LEPs have no filament or electrodes to burn out and thus will keep on producing light, although at declining levels and with a gradual shift in color, beyond their useful life. And, since a LEP (like an LED) has a comparatively very long life (as conventionally defined), over which its' lumen output drops continuously, it also has an appreciatively greater lumen depreciation over that life than does an HMI lamp. Given their continuous lumen depreciation and color shift over time, it is clear that there comes a time when a LEP bulb has surpassed its’ working life and should be retired. Since it won't burn out in its' prime, like an HMI lamp, how do we determine when a LEP has surpassed its' useable life. Clearly, this new technology requires a new approach to determining useable "lamp life" than that used for conventional lamps like HMIs. For instance, how useful is Photon Beard’s "lamp life" of 20'000 hours when according to Luxim’s specifications the bulb’s lumen output will depreciate as much as 60% with a color shift of 1000K (from 5300K to 4300K) in that time. Whatever the stated lifetime of any emitter technology, it must reflect a meaningful statistical measure of the performance of it in a given fixture design for a specific application. Clearly, in the case of LEP luminaries to be meaningful "lamp life" must be defined as the point of unacceptable lumen depreciation and color shift for our particular application rather than complete failure to light. And, whatever level of lumen depreciation is chosen for “low-light failure”, to be meaningful to it's users, it should be in line with existing lamp technologies used in that industry. In the case of motion picture lighting, I would argue that nothing short of a L85 criteria would be appropriate and meaningful, since that has been our experience with both HMI and Tungsten Lamps (where the “rated life” is the interval in which 50% of lamps fail and with an average lumen depreciation of 80-85%.) If we adopt this criteria for motion picture lighting applications of LEPs, their rated lamp life would still be an unparalleled 5000 hrs (compared to 500-750 hrs for HMIs and approximately 1500 hrs for LED fixtures.) In other words, the interval in which the output of an LEP drops-off of to 85 percent of its’ original value (L85) is 5000 hrs. Unlike an LED fixture that has no replaceable parts, the bulb of an LEP can be replaced after reaching this “low-light failure”, so the fixture does not have to be thrown away as is often the case with LEDS (see newsletter article for details.) Where we are a long way off from having a single-die LED with sufficient output and correlated color temperature to match HMIs, LEP lamps are a cost effective alternative to expensive HMI Fresnel systems when it comes to generating daylight balanced light. In fact there is one LEP head that we are looking at (not the Photon Beard Nova 270 – it’s too expensive) because it has a Power Factor of .99 making it a near linear load. As a result, it uses power more efficiently, minimizes return current, and generates virtually no line noise. Where, it is as much the Harmonic Noise that non-PFC HMI, Fluorescent, and LED power supplies kick back into the power stream, as it is their higher Apparent Power, that limits the total number of them that can be reliably operated on conventional portable generators; the efficiency and near unity Power Factor of this LEP head means that you can operate more of them on portable gas generators. For instance, you can operate four 575W HMIs on a 6500W portable AVR generator, where you should be able to operate 23 of these 270W LEP heads (each with an output comparable to a 575W HMI). Oscilloscope shots comparing the current and voltage waveforms of the PFC Helio 270 with an equivalent wattage of non-PFC LEDs Where LEP is radically new technology there is a lot to get your head around. One way to think of a LEP bulb is as a tiny discharge lamp. But, unlike an HMI bulb it does not have electrodes. Instead of applying a voltage and drawing a current through the lamp to create light as does an HMI, the energy that creates light in an LEP comes via a high frequency RF transmitter. The RF waves heat the materials inside the lamp and bring those materials to a plasma state so that the lamp emits a "flicker-free" light. Besides better color rendering, light quality, and lamp life, this different method of transforming electricity into light has other benefits as well. For more details about LEPs see our newsletter article at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html#anchorHigh%20Output%20LEPs. Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental & Sales in Boston

Light emitting Plasma, or LEP, is getting a lot of press lately. However, you have to be wary of all the claims made by head manufacturers. Whenever a new lighting technology comes on the market, the manufacturers put a little spin on the scientific data (LED manufacturers do this still), which has a tendency to cloud issues. For this reason, to pick the right LEP luminary for a particular job it helps to have a little knowledge of the technology. For our company newsletter I have put together an overview of the technology and what products are available for motion picture lighting (available at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html#anchorHigh%20Output%20LEPs.) In this newsletter article I have tried to cut through some of the hype. Here is a quick summary of a few of the issues. Yes, LEP bulbs are capable of intense light output. One manufacturer, Luxim, claims their technology can produce 144 lumens per watt. In contrast, Tungsten Halogen bulbs produce 15 lumens per watt, LED emitters produce between 65 to 85 lumens per watt (in practical applications), and HMI bulbs produce 90 Lumens per watt. While there is truth in this claim as it pertains to an LEP bulb in isolation, as with LEDs, manufacturers have not realized anything close to that kind of lumen efficiency within the framework of a practical light that will burn in all lamp orientations. The Helio 270 LEP When the pill sized LEP bulb in mounted in the “puck” so that it will burn in all head orientations, the emitting area is no more than 1/4" x ¼." In this configuration, the 273W LEP bulb will deliver 16000 lumens or 57 lumens per watt. While much less than the 37’000 lumens the bulb will generate fully exposed in a horizontal position, it cannot be tilted up in that orientation. On the plus side, mounted so that it will burn in all orientations, all of its’ output is forward directed within a 60 degree angle so it doesn’t require a reflector. Such a highly localized forward directed light is ideal for Fresnel type instruments. As close an approximation to the ideal point source that exists today, its light output favors the central portion of the Fresnel lens. Since, this part of the lens has greater transmittance, LEPs are a more efficient source for Fresnel type heads than tungsten filaments, LED arrays, and even HMI arcs. For this reason you get more of those lumens transmitted through the lens in a highly collimated light that is very clean and crisp making it great for cutting shadows or gobo effects. The 273W LEP bulb in a Fresnel type instrument has an output comparable to a 575W HMI Fresnel. Forward directed output of Helios 270 LEP LEP head manufacturers also claim that LEP lamps provide a CRI of 94+. While impressive, CRI ratings published by manufacturers can be misleading. Where the CRI index indicates the ability of a light source to reproduce to the eye only 8 colors faithfully (a different 8 colors are used in Europe) they should be taken with a certain amount of skeptism. In the case of LED luminary manufacturers, for instance, it is possible to tune their output to the limited color range of the CRI color scale and deliver good color rendering to the eye while delivering generally poor color reproduction on the screen. More important than their high CRI ratings, is the fact that LEP lamps generate light with a continuous color spectrum. If you compare the spectral power distribution graphs (above) of natural daylight and LEP lamps (available at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html#anchorHigh%20Output%20LEPs) you see that, except for very brief drop outs at approximately 425 nm and again at 475 nm, the light output of LEP lamps is almost identical to natural daylight. And, as also can be seen in their spectral distribution graphs above, Plasma lamps have a much more continuous color spectrum than even the best LED luminaries on the market today. For instance, LEP lamps, unlike LED lamps, generate light at wavelengths shorter than 425nm - which means that violet colors will render better. And, unlike LED lamps, LEP lamps also output in the medium blue-cyan-turquoise range from about 465-510nm so aqua-type colors render well by comparison. Skin tones and warm, amber-yellow colors stand out better under LEP lamps because of the strong presence of their complementary colors. And, since the output of LEP lamps extend all the way out on the long-wavelength end (well beyond the 600 nm cutoff of LEDs), pinks, reds, oranges, and other long wave-length colors look vibrant under LEP light where they tend to look a little dull under LEDs. As a continuous spectrum source, colors not only appear more natural and vibrant under LEP lamps than under LED lamps, they also reproduce more accurately on the screen since, as is also evident by their spectral distribution graph, the output of LEP lamps is almost an exact match to the spectral sensitivity of daylight film emulsions and digital sensors. Plasma lights will deliver the same true-to-life color rendition previously achievable only with full-spectrum Daylight or HMI sources. As an added bonus, color meters, like the Minolta III F, that make their calculations of the Color Temperature (CT) based on a light sources continuous spectrum, are able to generate accurate reading of the CT and Green/Magenta of LEP lamps where they are almost completely useless with LEDs. Another feature of LEPs that has been overblown is their purported 20-30’000 hr lamp life. But, where I am out of space here, I will pick up with that issue in my next post. Guy Holt, Gaffer, ScreenLight & Grip, Lighting Rental & Sales in Boston

If the A-H Hart-Lock 600V 50A twist lock receptacle is on a single phase service (you read 240V between the two hot pins) you can safely and legally use a transformer as a distro as Eileen suggests. I have used the same transformer/distro that we make to step down the enhanced 7500W output of our modified Honda EU6500, to power Quartz lights up to 5k and even HMIs as large as a 4k on 50A/240V range receptacles as well as 30A/240V dryer receptacles. Other common 240 volt wall outlets are air conditioner outlets, outlets for large copy machines in offices, and the outlets for motorized equipment and compressors in industrial plants. Like the A-H Hart-Lock 600V 50A twist lock receptacle in your schools studio, if you look at the breaker of these circuits on the building service panel you will notice that they use two pole breakers - either 30A or 50A. Each pole of the breaker is in a sense an independent 30A or 50A 120 volt circuit. That is, if you measure the voltage from each pole of the breaker to ground it will be 120 volts, and if you measure the voltage between the two poles of the breaker you will notice that it is 240 volts. The 120 volts of the two poles adds up to 240V because the 120V circuits are on opposing legs (and are therefore additive) of either a single phase electrical service of a house, or a single phase secondary step down transformer of an office or industrial plant. In residential settings, this is how higher voltages are supplied to household appliances like Dryers, Electric Ranges, Air Conditioners, and Heaters that require more power than can be reasonably supplied by a single 120V circuit. Many of these household and industrial 240V receptacles use a three wire system (no neutral) because they are designed to power single phase motors or heating elements that draw a perfectly balanced load and return no current because the single phase service legs are 180 degrees out of phase and cancel each other out. The voltage of opposing legs of a single phase circuit add while the current carried on the legs subtract. You run into trouble when you try to use a "Splitter Box" (like the one at Kayelites) without a neutral when you start to pull an unbalanced load. Since under most production situations you can never perfectly balance your lighting load, the two 120V circuits that make up this 240V circuit will not have 100% phase cancellation and the extra current of the high leg will not have a safe return path because by necessity with a three wire system, like this A-H Hart-Lock 600V 50A twist lock receptacle, you have had to bond the ground and the neutral in the splitter box (after all what else can you do with the ground and neutral of your splitter box but to bond them when plugging into a three wire 240V circuit.) There are some people that will argue that it is not such a big deal to carry current on the ground wire. I would argue that it is both unsafe and unwise to carry current on the ground wire. It is unsafe because the ground wire is intended only as a default conduit in the event of equipment failure (which is why it is permissible according to the National Electrical Code (NEC) to use a smaller conductor for the ground wire.) It is unwise because bonding ground and neutral after the service side of a main service head (which is what you have to do with the ground and neutral of a splitter box when plugging into a three wire 240V circuit.) is a violation of the NEC. To quote Mike Holt, of Mike Holt Enterprises, Inc. again: “The National Electrical Code (NEC) requires a neutral-to-ground connection to be made at service equipment only and there shall not be any neutral-to-ground connection on the load side of service equipment [250-23(a), 250-24(a)(5)]” (full excerpt is available online at his website) If some one were to fall off a ladder because they took a non-lethal shock because the cable they were handling was carrying current on the ground wire your liability insurance would be null and void because you were using equipment that need not meet code. 4k & 1.2ks HMI Pars powered from 30A/240V dryer outlet through step-down transformer/distro for Bose still shoot. The only safe way to pull power from 3-wire 240V circuits (hot, hot, ground, no neutral) that meets the requirements of the National Electrical Code is to run your lighting load through a 240v-to-120v step down transformer. A transformer converts the 240 volts supplied by these industrial and household 240V receptacles back to 120 volts in a single circuit that is the sum of the two legs of the circuit. For instance, a transformer can make a 60A/120v circuit out of a 30A/240v dryer circuit that is capable of powering bigger lights, like a 5k. What makes it safe to use a step down transformer is that the transformer automatically splits the load of whatever you plug into it evenly over the two legs of the 240V circuit. Where there is no high leg, the loads on each leg of the 240V circuit cancel out and there is no return that would require a separate neutral. Unlike a 240V "Splitter Box" where you have to meticulously balance your load, a transformer greatly simplifies your set electrics by automatically splitting the load. As long as you plug lights in through the transformer, you no longer have to carefully balance the load over the two 120V circuit/legs because the transformer does it for you automatically. If you outfit the transformer with a 60 Bates receptacle, you can use 60A GPC extension cables, 60-to-60 Splitters, and fused 60A GPC-to-Edison Breakouts (snack boxes) to run power around set - breaking out to 20A Edison outlets at convenient points (rather than one central point.) The best part about using a transformer with a 240V receptacle in this fashion is that no matter where in the distribution system you plug in, the transformer automatically balances the additional load, so that you don't have to. A Distro System consisting of a 60A Full Power Transformer/Distro, 2-60A GPC (Bates) Splitters, 2-60A Woodhead Box distributes power from a modified Honda EU6500is. Even though the generator is 100' away to reduce noise, plug-in points remain conveniently close to set. I use transformers to power bigger HMIs (2.5-4Kw) in situations where a tie-in is not an option and the budget doesn’t permit for a tow generator. Where the production budget is particularly tight, I use a package consisting of two transformers and a portable generator. I use one transformer to access more power through a 240V circuit on location to run lights inside; while the other I use our our modified Honda EU6500is generator to bring larger HMIs in the windows from outside. This approach eliminates the need for a dangerous tie-in or expensive tow generators, it also greatly reduces the amount of cable that has to be run. Wide Shot of Night exterior scene lit with our HD P&P Pkg. For those who would like to see samples of what can be accomplished with this basic package, I have attached these links to production stills of the PBS and History Channel historical documentaries shot entirely, or in part, with just a couple of transformers and a Honda generator. The History Channel’s “Unsolved History” episode “Presidential Assassins” American Experienes Typhoid Mary Biography "The Most Dangerous Women in America" WGBH’s Ben Franklin Biography “Franklin” Or, use this link for more details about using step-down transformers on set: . By giving you access to more house power through common 240V house outlets, a transformer can quite often eliminate the need for tie-ins or generators. - Guy Holt, Gaffer, ScreenLight & Grip, www.screenlightandgrip.com

I have always found reflector boards to be useless under the dense foliage of woods because, except for an occasional shaft of light breaking through the leaf canopy, there is usually little direct sun to bounce. Even when you work on the edge of a clearing, the window of direct light is usually very short because of the surrounding trees quickly block the sun as it moves across the sky. Shooting in woods you definitely need lights and, I agree with the others, you will definitely need more than just a 1k. If you plan your shots properly, you can get away with nothing more than a 4k Par and 1.2 Par which you can run on one of our modified Honda EU6500is/Transformer gen-set that provides a single 60Amps/120V circuit. The approach that I find works best is to shoot the establishing master shot when the sun is in a backlight position. Up to that point I shoot the close coverage under a full silk. Shooting the coverage under a silk offers a number of advantages. If the sun breaks through the canopy, the silk takes the directionality out of the sun and knocks down its’ level by two and half stops. Now a smaller HMI light will have more of a modeling effect. Shooting into talents' down side under a silk, I find that a 4k Par through a diffusion frame is a sufficient key source for a two shot. If you wait to shoot the wide coverage until the sun has moved around to a back light position, your background is also back-lit so the discrepancy in exposure between the background and your talent to camera is not that great and so you can open up to gain exposure of your talent in the foreground without burning out the background. Also, when your background is back-lit, it does not over expose because of the discrepancy in levels under the silk and outside the silk – it helps to strike a good balance. Also, your background looks better because it is not flatly lit, but has some contrast. Finally, with the sun in a backlight position, if it comes through the canopy, the shadows of the silk frame and stands are thrown forward, which enables you to frame wider before picking up the shadow of the hardware. A good example of this approach is a scene I lit for a low budget feature that took place around a campfire in a small clearing surrounded by woods. Surrounded on all sides by woods, we knew that we would lose direct sunlight in the clearing early in the day and would need lights. We also knew that the scene was going to take all day to shoot because of its’ extensive dialogue, so we figured out where the sun was going to be throughout the day and where it would look best for our establishing wide shot. Where it was a two shot, mostly over the shoulder of one character talking to the second character who was standing with his back to the campfire with the woods behind him, we decided to wait until the sun had moved into a near back light position to shoot the establishing shot. So we shot our close coverage first with nothing more than a 4k Par and 1.2k Par under a 20x light soft frost on top of which we threw leaves. The 4k was heavily diffused and positioned so that it gave the talent the most attractive modeling. The 1.2kw was positioned as a backlight where the sun would be when we would eventually shoot the wide - this way there was always an edge in every shot for continuity. When the time came to shoot the establishing shot, the shadow of the overhead frame and stands were thrown forward and did not interfere with the wider framing. Since we were still shooting under the Frost, we were wider open on the iris and so our exposure dug into the dark woods and brought out more detail. As an unexpected added bonus, the smoke from the campfire drifted into the woods, creating shafts of light where the sun broke through the tree canopy. What would have been a high contrast scene without lights, turned into a beautifully lit scene, and was accomplished without a lot of amps. The whole scene was lit with nothing more than a 4k and 1.2k Par and powered by nothing more than a 60A/120 circuit from a modified Honda EU6500is/Transformer Gen-set. Guy Holt, Gaffer, Screenlight and Grip, Lighting rental and sales in Boston.

http://www.cinematography.com/index.php?showtopic=51247 Even though $3k is a sizable chunk of change for an LED light, this one is worth it I think. Up until now I was of the opinion that except for special applications requiring battery operation or for travel kits, LEDs did not offer sufficient additional benefit in general production applications to justify the cost – especially when the technology was evolving so rapidly that anything you purchase would be obsolete in a year or two. But, I think that Arri did several things right with the L7 that changes the cost/benefit calculation of LEDs. Knowing that their LED Fresnel line was going to be more costly per lumen than other light sources, Arri realized that there had to be an additional benefit or savings to justify the additional expense for them to be successful in market segments other than Broadcast Studio Installations. The benefit in the broadcast studio market is compelling: when you take into account the savings in power consumption (not only by the lights but also air-conditioning), lamp longevity (no need to replace burnouts), and gel longevity (no need to replace burned through gels), the benefits clearly outweigh the additional cost. On their website, Arri estimates that a studio with 50 1kw instruments will save approximately $148,000 over a five year period by using the L7 LED Fresnel instead. The “green” benefit is also compelling. Using L7s in place of 1kw Quartz Fresnels would save 450 tons of Co2 emissions and 964 barrels of oil. Or to put it another way, the use of 1kw Quartz Fresnels would require the planting of 10,600 trees to offset the additional carbon footprint. Without a doubt, the saving to be gained in the Broadcast Studio market more than offsets the additional expense of an LED Fresnel fixture. But since the same cost/benefit analysis isn’t as compelling in location production applications, Arri added several features not necessary for studio applications, that would make the benefits outweigh the additional costs for small production companies and camera owner/operators. One feature that offers tremendous benefit in location production is the fully tuneable color blending multi-emitter LED engine that they offer in the L7-C model. Capable of full spectrum tuneable white light with a CRI and CQS greater than 90, this LED engine makes the L7-C fully compatible with existing Tungsten as well as Daylight Light sources and makes it able to match to mixed-light environments without sacrificing output to color correction gels. Tuneable white light is a feature that benefits Red users, as well as users of DSLRs, in particular. One downside to lighting for sensors with a native color balance of 5000K in the past has been that it requires an all 5000k balanced lighting package and HMIs are considerably more expensive to buy or rent. Kino Flo fixtures, particularly the Parabeams, were a cost effective alternative to HMIs because they could use either 3200K or 5500K tubes. But, the drawback to fluorescent fixtures has always been that they generally have a very broad soft light output that drops off rapidly which means the units need to be positioned close to the subject they are lighting. This characteristic has always made them better suited to lighting documentary interviews than dramatic scenes. With a 5600K output comparable to that of a 575 HMI Fresnel, the Arri L7-C offers the same benefit of being a less expensive alternative to HMIs, but also the added benefit of being more versatile than a Kino Flo. Not only does it offer the capacity of traditional Tungsten/HMI Fresnels to throw and control its light output (making it a more suitable Key and Backlight source for lighting dramatic scenes), but it also has sufficient output to bounce it or waste some output to diffusion material to make it softer (existing LEDs put out barely enough, with none to waste.) It’s capacity to provide both hard crisp light that will throw a distance and is easily controlled, as well as offer soft light with diffusion, makes the L7-C much more versatile than any Fluorescent or LED light presently available. One L7-C will be able to do what it takes four Litepanel 1x1s to accomplish (spot and flood in 5600K and 3200K color temps) and more. Another feature that Arri has included in the L7s to benefit location production is Power Factor Correction (PFC.) Without a doubt, the even greater reduction in power consumption, and particularly line noise, that Arri achieves (that other LED manufacturers don’t) by incorporating PFC into their L7 Fresnels offers location productions an even greater cost benefit: not having to rent a movie blimped tow generator, with all of its’ hidden costs, in order to obtain decent production values. Until recently, to power a lighting package sufficient enough to get good production values required a large diesel tow generator. Movie generators are not only expensive to rent, but they come with hidden costs that usually break the budget of modest HD projects. Movie generators require special tow equipment not found on Ryder or Penske rental trucks. For that reason, movie generators require that you rent a more expensive grip truck from a lighting and grip rental company in order to tow them. Lighting rental companies will not send out a grip truck without a company driver - further adding to the expense of renting a movie generator (in this market driver rates run about $500/10hrs with overtime after 10hr). One of only a few LEDs available with PFC circuitry (and the only Fresnel with it), the L7 Fresnels will create virtually no power waveform distortion when operating on portable gas generators. For this reason, the generator will be capable of operating larger, or more smaller, lights than it could otherwise. With PFC in all your heads, you can load an inverter generator to capacity (use this link for details.) Which, in the case of our modified Honda EU6500is means the ability to operate up to 30 Arri L7s – effectively eliminating the need for a diesel generator in some situations. Even when you require a bigger gun like a 4k Par, the low line noise and power consumption of the Arri L7s make it feasible to operate an entire location package from a single Honda EU6500is. For instance, you can operate up to 10 L7s in addition to a 4k Par on the enhanced 7500W power output of our Honda EU6500is. And, since, Arri plans to introduce the ARRIMAX reflector technology to the 4k HMI power class (resulting in a head with the output and light quality of a 12kw Fresnel that can operate on a portable Honda generator), what can be accomplished with a portable gas generator will be tremendous when used with camera systems like their Alexa (that is capable of a fourteen stop exposure range and ASA sensitivities of 1600 without grain.) With Power Factor Corrected L7 LED Fresnels, ARRIMAX reflector HMIs, and Kino Flo Parabeams, you won’t need anything more than can be operated on the enhanced 7500W output of a Honda EU6500is to get decent production values in most production situations – effectively eliminating the need for a large diesel tow generator, with all its hidden costs. This is what has Harry Box so pumped about our HD Plug & Play Gen-set and why he has included it in the 4th Edition of his “Set Lighting Technician’s Handbook” ( use this link for details.) When you start to use the new math of not only lower power consumption, but also of lower line noise, to calculate what can be operated on a portable gas generator, you quickly realize that the savings of not having to rent a large diesel tow generator to get good productions values starts to outweigh the additional cost of the Arri L7s. And, when you factor in the hidden costs of renting a large diesel tow generator – the rental house grip truck, truck driver to tow it, and the extra electrical crew to distribute the power – the cost savings more than offsets the additional cost of the L7 LED Fresnel. The final thing Arri did that makes me feel comfortable investing in them, was to build the L7 on an expansible platform. Not only, do the heads allow for the incorporation of more efficient LED chips when they become available, but the light engine is also fully upgradeable, ensuring that the fixtures can take advantage of technology advances as they happen. To accommodate future control protocols (such as ANC), their firmware is also upgradeable through the USB port on the rear of each unit. They are also compatible with planned future optic accessories that will expand the L-Series versatility. Able to incorporate future developments in LED technology, the expansible platform of the L7s ensures that they will have a long useable life and so will assure a return on investment in them. Given the rapid pace of LED chip development, I can’t think of another LED fixture that won’t be obsolete in a year or two, making the Arri L7 Fresnels the safest investment out there. - Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental and Sales in Boston.

In a permanent install application in a studio there is no need for the color tuning feature of the L7-C so why pay the extra amount whatever it is. When you are looking at buying 30 heads for a studio build out, I am sure the difference adds up. Same is probably true of newsrooms that have windows to the outside - why pay for color tuning when all you will ever use is 5600. Look for a new thread on the LED Fresnels being exhibited at NAB this year that I am starting http://www.cinematography.com/index.php?showtopic=51247 - Guy Holt, Gaffer, ScreenLight & Grip, Lighting & Grip rental & sales in Boston.

I have been following the development of LED Fresnels with interest and so couldn’t wait to see what would be introduced at NAB this last weekend. I am happy to report that definite steps have been made in developing a production LED Fresnel light that combines the advantages of LED illumination (cool-burning, energy-efficient) with the versatility and control of traditional Fresnel fixtures. To reach this point, manufacturers of LED fixturess had to overcome a number of problems. The biggest problem of LED lights in the past was their poor color rendering (use this link - http://www.oscars.org/science-technology/council/projects/ssl/index.html - to the Academy of Motion Picture Arts & Sciences’ “Solid State Lighting Project” for details.) In addition to having poor CRIs, LED output and color decays with age, making their color rendering capability inconsistent at best. A second problem inherent in LEDs that manufacturers have had to address is the relatively poor power quality generated by the Switch Mode Power Supplies (SMPSs) they use to power their lights on AC power. With Leading Power Factors around 0.54 (Litepanel 1x1s) and high harmonic distortion (THD upwards of 68.1%) the AC power supplies of LEDs have generally drawn a very distorted current that is significantly phase-shifted with respect to the sinusoidal voltage waveform. As such, the AC power supplies of LEDs have had an adverse effect on power quality similar to that of CFLs (use this link for more details.) Finally, another drawback to LED fixtures until now is that the "light panel" design creates a light that is hard to control and falls off very rapidly. These characteristics have made LED light panels only suitable as Key sources in documentary interview set-ups where the Keys are typically positioned close to the interview subject. In that capacity LED light panels (with heavy diffusion) can generate a wonderful soft light that wraps around the interview subject without wilting them. However, in dramatic set lighting, where Key sources must be capable of throwing a distance, LED light panels have only limited applications as fill sources. The broad soft light they put out drops off too rapidly, and is too difficult to control, for them to be effective as a Key or Backlight source in dramatic set lighting. For LEDs to be widely used, manufacturers had overcome these shortcomings - their poor color rendering, poor power quality, and lack of versatility - to previous LED light designs. As I said at the outset, progress has been made on many of these fronts in the fixtures being introduced at NAB this year. Particularly in the case of the Litepanel Sola 6 Fresnel and the Arri L7 Fresnel. The Litepanels Sola 6 LED Fresnel While the Sola 6 Fresnel is definitely a step in the right direction in developing a production LED, far as I am concerned, Litepanels has not completely overcome all of the shortcomings outlined above with the Sola fixtures. Litepanels doesn’t give CRI ratings for the Sola Fresnels on their website, but when asked they say the CRI is in the 80s – which is still rather anemic compared to continuous spectrum light sources like quartz and HMI lights. The Power Factor of the Sola has been improved. But, at .85 it could stand further improvement (a Power Factor Corrected HMI has a Power Factor of .98 or near unity power.) They claim the 75W Sola 6 has the output equivalent to a 650W Tungsten, but comparing the photo-metrics published on their website to those of an Arri 650 Fresnel, the Arri has nearly three times the output of the Sola. And, while the Sola 6 has an impressive spot to flood range (10 to 70 degrees), spot/flood capability is not the only characteristic that makes a Fresnel light versatile. Of equal importance is the ability to render clearly defined shadows and cuts. The ability of Fresnels to render crisp shadows make them ideal for creating gobo effects like window or branch-a-loris patterns. The ability of Fresnels to render clearly defined cuts enables their light to be precisely cut to set pieces and talent. And, simply by adding one of a variety of diffusion material you can vary the softness of a Fresnel’s output. These are the characteristics of traditional Fresnels that make them extremely versatile, that the Sola “Fresnels” have not been able to emulate. The Arri L7 LED Fresnel Arri, on the other hand, may have finally engineered in their new 200W L7 LED Fresnel a fixture that combines the cool-burning, energy-efficient advantages of LED illumination with the controllable versatility of traditional Fresnel fixtures. As you can see in the pictures above, that compare the output of the L7 Fresnel to an Arri ST-1 Quartz Fresnel, the L7 Fresnel has clear and defined shadow rendering capability like that of the ST-1 Quartz Fresnel. And, as the pictures below demonstrate, the L7 Fresnel has a spot to flood range similar to that of the ST-1 Quartz Fresnel and excellent field homogeneity in both flood and spot. And, just like the ST-1 Quartz Fresnel (pictured below), the beam of the L7 Fresnel (pictured above) is easily controlled with barndoors - enabling the light to be precisely cut to set pieces and talent (see far right photos above & below.) And, given the discernable amount of light the L-Series Fresnel prototypes threw in a show demonstration video from IBEC last fall, on what appears to be a 6x6 Ultrabounce rigged 20’ overhead, and under the high ambient light levels of the show hall, it seems the production model L7 Fresnel has more than enough output to waste some to diffusion and color gel if one so desires (a shortcoming to most LED panels is that they have barely enough.) The L7 line of LED Fresnels introduced at NAB consists of three models: the L7-D, L7-T and L7-C. All share the same basic housing and the same 7" Fresnel lens, and all have output comparable in intensity to a conventional 1K Fresnel. They differ in terms of color temperature, with the D model outputting a daylight-equivalent 5600 K, the T model a tungsten-equivalent 3200 K, and the top-of-the-range C model offering total color control. In my opinion, the Arri L7s finally deliver the true-to-life color rendition, previously achievable only with full-spectrum tungsten sources. By color blending with a multi-emitter LED engine, the L7 is able to overcome the generally poor color rendering capabilities of other LED fixtures. Both the 3200 K and 5600 K color temperature models offer a CRI and CQS greater than 90 so skin tones, costumes and scenery will finally appear life-like under LED light.
 The L7-C’s fully tuneable white light can be adjusted for different skin tones, camera sensors and mixed-light environments, while specific color shades can be matched through full gamut color mixing. Unlike other LED fixtures, this level of color control does not involve compromising the quality of the light field: the L-Series is unique in combining uniform light and single shadow rendition with absolute control of color attributes. Split Macbeth chart: each color patch shows the visible effects of studio tungsten light in the top half of the patch, and a representative multi-emitter LED lighting instrument in the bottom half. Note: this is not the L7 but results typical of the multi-emitter LED approach An added benefit to using a color blending multi-emitter LED engine is that the L7’s firmware can calibrate the blend of different color emitters to compensate for the inevitable color shift of the LEDs with age. This approach assures consistent realistic color rendition throughout the fixture’s life. There are two alternative cooling systems: one passive and the other active. The passive cooling system was designed for broadcast studios. It incorporates no moving parts or fans and is therefore completely silent. The active cooling system was designed to provide a more compact and lightweight option for location work. It uses an extremely quiet (<20 dB) fan and weighs 10lbs less than the studio version. The location fixture carries an IP54 rating for weather resistance which means that it is protected from falling rain and splashing water, and that the internal electronics, optics and LEDs are protected from dust, dirt and humidity – making it a very robust fixture that will stand up to the rigors of location production. All the L7s feature Power Factor Correction with a near unity Power Factor of .91. Which means that the 200W fixtures will draw no more than 1.98A at 120V (220W) and cause virtually no Harmonic Distortion. Since it creates virtually no line noise, you will be able to power nine 200W L7s on the 20A circuit of a portable generator without a problem. And since the L7-T has an output comparable to a 1k Quartz Fresnel, and the L7-D has an output comparable to a 575W HMI Fresnel, the L7 series takes what you can do with a portable generator to a new level. For example, with the enhanced 7500W output of our modified Honda EU6500is, you will be able to operate a lighting package consisting of a 30 L7s. I think you would have to agree that is an incredible step-up in production capability. At a price around $2’500, the L7s are one of the more expensive LED fixtures at NAB. But, to assure that they are not quickly rendered obsolete by the rapid advances being made in LED chip efficiency, Arri has designed them to be an expansible platform that can incorporate future developments in LED technology. Not only, do the heads allow for the incorporation of more efficient LED chips when they become available, but the light engine is also fully upgradeable, ensuring that the fixtures can take advantage of technology advances as they happen.
 To accommodate future control protocols (such as ANC), their firmware is also upgradeable through the USB port on the rear of each unit.
 They will also be compatible with planned future optic accessories that will expand the L-Series versatility. Able to incorporate future developments in LED technology, the expansible platform of the L7s ensures that they will have a long useable life and so will assure a return on investment in them. Given the rapid pace of LED chip development, I can’t think of another LED fixture that won’t be obsolete in a year or two. The scheduled release for the L7 LED units is September 2011. With the same clear and defined shadow rendering, excellent field homogeneity, and smooth continuous flood to spot focus as a 1kw Quarts Fresnel, these first production models of the L-Series LED Fresnels may well be the first true LED Fresnel lights (use this link for more details.) For more detailed information on the Power Quality generated by LED power supplies and to see a demonstration video of the new Arri L-Series LED Fresnels, use this link to an article I wrote for our company newsletter on the use of portable generators in motion picture lighting. In it I cover some of the basic electrical engineering principles behind LED drivers, the harmonic distortion they can generate, and how it can adversely affect generators. The article and the demonstration video are available online at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html. Guy Holt, Gaffer, ScreenLight & Grip, Lightng & Grip Rental in Boston

Word from NAB is that the L-Series LED Fresnels being introduced by Arri this week are a line of three 200W heads. They consist of the L7-D, L7-T and L7-C. All share the same basic housing and the same 7" Fresnel lens, and all have output comparable in intensity to a conventional 1K Fresnel. They differ in terms of color temperature, with the D model outputting a daylight-equivalent 5600 K, the T model a tungsten-equivalent 3200 K, and the top-of-the-range C model offering total color control. All offer a CRI and CQS greater than 90 so skin tones, costumes and scenery will finally appear lifelike under LED light. There are two alternative cooling systems: one passive and the other active. The passive cooling system was designed for broadcast studios. It incorporates no moving parts or fans and is therefore completely silent. The active cooling system was designed to provide a more compact and lightweight option for location work. It uses an extremely quiet (<20 dB) fan and weighs 10lbs less than the studio version. The location fixture carries an IP54 rating for weather resistance which means that it is protected from falling rain and splashing water, and that the internal electronics, optics and LEDs are protected from dust, dirt and humidity – making it a very robust fixture that will stand up to the rigors of location production. All the L7s feature Power Factor Correction with a near unity Power Factor of .91. Which means that the 200W fixtures will draw no more than 1.98A at 120V (220W) and cause virtually no Harmonic Distortion. Since it creates virtually no line noise, you will be able to power nine 200W L7s on the 20A circuit of a portable generator without a problem. And since the L7-T has an output comparable to a 1k Quartz Fresnel, and the L7-D has an output comparable to a 575W HMI Fresnel, the L7 series takes what you can do with a portable generator to a new level. For example, with the enhanced 7500W output of our modified Honda EU6500is, you will be able to operate a lighting package consisting of a 30 L7s. I think you would have to agree that is an incredible step-up in production capability. At a price around $2’500, the L7s are one of the more expensive LED fixtures out there. But, to assure that they are not quickly rendered obsolete by the rapid advances being made in LED chip efficiency, they are designed to be an expansible platform that can incorporate future developments in LED technology. Not only, do the heads allow for the incorporation of more efficient LED chips when they become available, but the light engine is also fully upgradeable, ensuring that the fixtures can take advantage of technology advances as they happen.
 To accommodate future control protocols (such as ANC), their firmware is also upgradeable through the USB port on the rear of each unit.
 They will also be compatible with planned future optic accessories that will expand the L-Series versatility. Able to incorporate future developments in LED technology, the expansible platform of the L7s ensures that they will have a long useable life and so will assure a return on investment in them. Given the rapid pace of LED Chip development, I can’t think of another LED fixture that won’t be obsolete in a year or two. With the same clear and defined shadow rendering, excellent field homogeneity, and smooth continuous flood to spot focus of Arri's ST-1 1kw Quartz Fresnel, these first production models of the L-Series LED Fresnels may well be the first true LED Fresnel lights (use this link for more details.) For more detailed information on the Power Quality generated by LED power supplies and to see a demonstration video of the new Arri L-Series LED Fresnels, use this link to an article I wrote for our company newsletter on the use of portable generators in motion picture lighting. In it I cover some of the basic electrical engineering principles behind LED drivers, the harmonic distortion they can generate, and how it can adversely affect generators. The article and the demonstration video are available online at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html. Guy Holt, Gaffer, ScreenLight & Grip, Lightng & Grip Rental in Boston

While I agree with you 100%, you also have to master your medium before you can create great works of art. You can be sure that the great painters through out history didn’t simply buy their pigments off the shelf of an artists supply store but instead mastered fundamental chemistry to create their own pigments. The same is true of our medium: if you don’t have a thorough understanding of your tools you will not be able to execute your artistic vision. For instance, if you are unaware, that the Leading Power Factor of lights that use Switch Mode Power Supplies (Electronic HMI, Fluorescent, & CFL ballasts, and LED power supplies) can cause them to use excessive amounts of power for the wattage of light they generate and to kick harmonics back into the power stream that can have a severe adverse effect on not only the generator, but also other electronic equipment operating on the same power, then you may never have the opportunity to create that great work of cinema because your HMIs wouldn’t hold their strike, your LEDs flickered, your Tungsten lights were excessively orange, your camera batteries wouldn’t charge, and your back up hard-drives locked up. For better or worse, cinematography is a technical medium. If you don’t master the technology, you will never have the control over the medium required to make great art. - Guy Holt, Gaffer, ScreenLight & Grip, Lighting rental & sales in Boston

Jonathan, To my list of issues particular to electronic HMI ballasts I would add use with Ground Fault Interrupt Circuits (GFCIs.) Again, you will find information in that newsletter article that is pertinent. - Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental and Sales in Boston.

Hello Jonathan, You must be a new reader to this forum, because you wouldn't be asking this question otherwise. First let me welcome you. Your question is a good one. There are a number of precautions you should take and special considerations when using electronic HMI ballasts. Special precautions should be taken in grounding, dimming, cooling, handling, color balancing, load calculation, sizing of neutral returns, condition of head cables, plugging them into house power and choosing a generator. Special considerations pertaining to electronic HMI ballasts include Power Factor, Harmonic Noise, and Power Quality. I would give you a quick summary of the issues pertaining to the use of electronic HMI ballasts, but some readers of this forum find it repetitive. So instead, as they would prefer, I will refer you to an article I have written on the use of portable generators in motion picture production for my company newsletter. The newsletter article includes answers to all of your questions but you will have to pick through over a hundred pages of other information, rather than have me summarize it for you, just so that other readers of this forum are not put out by too much detail that they can easily choose not to read if they don't want to. So rather than take the time and make an effort to thoroughly answer your questions, I will leave it to these other readers to take the time and make an effort to post a response that is more than a sentence or two to a very complicated question (somehow I doubt that they will.) But remember, even though it is cited in the just released 4th Edition of Harry Box's "Set Lighting Technician's Handbook" and featured on the companion website "Box Book Extras", and even though Harry Box exclaims of the article: "Great work!... this is the kind of thing I think very few technician's ever get to see, and as a result many people have absolutely no idea why things stop working." "Following the prescriptions contained in this article enables the operation of bigger lights, or more smaller lights, on portable generators than has ever been possible before." it is nothing more than an "infomercial" and not to be believed. My infomercial (I mean my article) is available online at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html. Good luck finding the answers to your questions. I wish I could be of more help, but I don't want to offend anybody. Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental and Sales in Boston

I just listed on ebay a Sales Demo Desisti 4k Par system with Power Factor Corrected Flicker Free Electronic Ballast. This is a rare opportunity. Once this sells, you will not find a complete 4k Par System with the latest Power Factor Corrected Ballast technology from a major manufacturer in this kind of condition for under $7000.00 again. You can buy directly at any time for the ebay opening bid amount as long as the item on ebay does not have a bid. If you want added security, you can partake in the ebay auction. As you can see from the screen grab of the present ebay auction, I have 100% positive feed back on my auctions so you can bid with confidence. Use the link below the screen grab to connect to the auction site. If the auction has expired, be sure to search for the item on ebay because it will be relisted if it did not sell. Demo Desisti 4K HMI Par w/ Flicker Free Electronic Ballast This 4k Par can serve as the backbone of a powerful HD lighting package when used in conjunction with our 7500W modified Honda EU6500is blimped generator. As long as there is a sun and moon in the sky there is the need for a large HMI like this Desisti on interior and exterior sets because smaller HMIs, Kino-Flos, & LED panels don’t come close to balancing direct sunlight in day light scenes or covering deep background in night scenes. For powerful daylight fill on exterior sets, to create the feel of hard sunlight on interior sets, or to light deep background on night exterior sets, a dual wattage HMI Par like this Desisti is invaluable because it will operate off our modified Honda EU6500is (pictured below) or off of regular wall outlets. New 7500W "Movie Blimped" Genny for Mole, Arri, Kino The Par configuration of this light not only give you more output, but is also extremely versatile. When you need a lot of light for fill on day exteriors you can lamp it with a 4k globe. To cut a hard window pattern, swap the standard spreader lenses for a Frosted Fresnel. When you don’t need the punch of a 4k Par, like on a night exterior, you can swap the 4kw globe for a 2.5kw globe giving you more power to run additional lights on a small portable generator. The 15 Amps you save by burning the smaller 2500W globe will power quite a few more lights when you consider that a Kino Flo Parabeam 400 uses only 2 Amps. For example, it is possible to power a lighting package that consists of PFC 1200, & 800 HMI Pars, a couple of Kino Flo ParaBeam 400s, a couple of ParaBeam 200s, and a Flat Head 80, in addition to this Desisti Par (with a 2.5kw globe) off of our modified Honda EU6500is Generator. Given the light sensitivity of the Digital SLR HD Cameras this can constitute a complete location lighting package for HD Digital Cinema productions. When you have a camera system like the Canon 1D, that offers a 35mm image sensor, interchangeable lens capability, and is capable of an ASA of 1000 without noticeable noise, you don't need much more light than we can run off our generator system. For details about powering these 4k HMI Pars on wall outlets and portable generators read our company newsletter article: “The Use of Portable Generators in Motion Picture Production.” This article is cited in the just released 4th Edition of Harry Box's "Set Lighting Technician's Handbook" and featured on the companion website "Box Book Extras." The article is available online at http://www.screenlightandgrip.com/html/emailnewsletter_generators.html. Of the article Harry Box exclaims: "Great work!... this is the kind of thing I think very few technician's ever get to see, and as a result many people have absolutely no idea why things stop working." "Following the prescriptions contained in this article enables the operation of bigger lights, or more smaller lights, on portable generators than has ever been possible before." Use this link for an informative newsletter article that explains the electrical engineering principles that make it possible for our modified Honda EU6500is to power bigger lights, or more smaller lights, than has ever been possible before of a portable generator. Financing is available on items over $5000.00. I accept Paypal from confirmed addresses only as well as Cashiers Checks, Money Orders, and Wire Transfers. If you have any questions, please don't hesitate to send me an email at rentals@screenlightandgrip.com or call 781-326-5088, Ext 5# for the Rental Dept. All Prices are in USD and do not include shipping. You are also welcome to pick items up personally in Boston, but you will then be subject to the 6.25% Massachusetts Sales Tax. - Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental in Boston, MA

Ignoring its’ Power Factor, a more accurate paper calculation for the 16 fixture Litepanel bank Phil refers to above would be 640W (16 x 40W) since according to the manufacturer, the AC-to-DC power supply that Litepanel uses for their 1x1 fixtures generates 24V DC and according to the Litepanel website the load of a 1x1 is 40W at 24V (its 45 Watts at 12V.) With a PF of .54 its’ actual load is 1185 Watts which is how I came up with the draw of 10A at 120V (it would be closer to 11 Amps at 110V.) Again, I don’t know the exact manufacturing cost to incorporating PFC circuitry in LED AC-to-DC power supplies, but apparently it is enough of a cost consideration to lead Litepanels to not incorporate it into the AC power supplies they use for the Litepanel 1x1s. Litepanel 1x1s use the Cincom TR70A24 SMPSs Type AC-to-DC Converter For the 1x1s they use the Cincom TR70A24 SMPSs Type AC-to-DC Converter (pictured above) which, to their credit, is by not means a cheap power supply. It boasts line regulation specifications of +/- 1%, load regulation of +/- 2%, and an efficiency of 84%. With specs like these you won’t see the flicker that you sometimes see in cheaper LED fixtures where the manufacturer doesn’t bother using a fully regulated DC output, but instead opts for poorly rectified AC. Distribution of harmonics generated by the power supply of the Litepanel 1x1 LED Fixtures. Note: predominance of the 3rd, 5th, 7th, and 9th harmonics that don't cancel on neutral returns. However, the Cincom TR70A24 also has a Leading Power Factor of .54 and a Total Harmonic Distortion (THD) of 68.1% (see chart above.) As such, it generates a very distorted current that is significantly phase-shifted with respect to the sinusoidal voltage waveform (see oscilloscope graph below), and when used in quantity on a conventional portable generator, can have an adverse effect on its power quality (see oscilloscope shot below), similar to that of the CFL bulbs in the You-Tube video I mentioned earlier. Voltage and Current waveforms generated by SMPS type AC-to-DC Converter used to drive AC LEDs. Power Factors for the power supplies used in the Litepanel line of LED fixtures range from 0.54 (Litepanel 1x1s), to 0.85 (Litepanel Sola Fresnels) where Zylight’s IS3 Intelligent Studio LED Light has a PF of .98 (but it costs $2,580 verses $1549.00 for a 1x1 Litepanel.) So obviously, for some reason Litepanels has decided not to incorporate it into their power supplies for the fixtures they market in this country. Perhaps because it is an unnecessary additional expense since Power Factor Correction (PFC) is not mandated in this country, as it is in Europe for any electrical device that draws more than 75W, or simply they felt it was not an issue where the typical application of the units involves only one or two fixtures. The type of voltage waveform distortion that can be generated in conventional AVR generators by SMPS type AC-to-DC Converter used to drive AC LEDs. However, as illustrated in the You-Tube video above, if used in quantity on a conventional portable generator, they can lead to the type of voltage waveform distortion in the oscilloscope shot above and so have an adverse effect on both the generator and other equipment operating on the same power (Use this link - http://www.screenlightandgrip.com/html/ema...generators.html - for a detailed description of the adverse effects that LEDs can have on portable generators.) Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental & Sales in Boston

And the point that a rig like the one Phil pictures above will draw nearly twice the load as you would think (10 Amps verses 5.33 Amps) because of their poor Power Factor and that their Leading Power Factor will have an adverse effect on conventional AVR generators and other equipment operating on the same power for the reasons discussed above. - Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental & Sales in Boston

I agree a hundred percent. We are no longer in our parent’s linear world. The power generation and electrical distribution systems developed then were much simpler. But, unfortunately they were not designed to deal with the abundance of non-linear loads like electronic HMI and Kino Flo ballasts that make up lighting packages today. It’s a problem that has only recently begun because of the increasing use of non-linear lighting loads. The problem is being further compounded by the increasing prevalence on set of sophisticated electronic production equipment like HD cameras, computers, hard drives, and monitors which are not only sensitive to harmonic distortion, but are themselves sources of harmonic distortion. 

 For instance, the self-excited AVR systems of conventional generators were not designed to operate with leading power factor loads. In AVR systems, the AC voltage generated is controlled by DC excitation of the electro-magnets of the generator's Rotor. The amount of DC excitation required is a function of generator load; or, put another way, the excitation required to maintain constant voltage increases with load. The type of load also affects the amount of excitation required. Lagging power factor loads (magnetic ballasts) require more excitation than a unity power factor load (Quartz Lights.) Leading power factor loads (electronic ballasts) require less excitation than unity power factor loads. 

Rudimentary AVR systems like those in portable generators are ill equipped to deal with leading power factor loads like electronic ballasts because the harmonic currents they generate create flux in the armature coils of the Stator that reacts additively with the Exciter flux in the field poles of the Rotor to increase saturation and produce a higher terminal voltage than called for a given load. Consequently, the AVR system responds erroneously to control voltage by reducing excitation. The end result is that the regulator goes to its minimum excitation capability while the additive excitation of the armature flux from the leading power factor causes the terminal voltage to continue to rise and not be controlled by the voltage regulator. 

 Erroneous regulation of voltage is just one example of the more severe effect that leading power factor loads have on conventional AVR generators than do lagging power factor loads. In researching my newsletter article I compared the characteristic voltage waveform distortion created by different lighting loads on different generators, and found that leading power factor loads also have a more severe effect on other production equipment operating on the same power. Use this link for my newsletter article that explains the electrical engineering principles behind these issues and how to resolve them. - Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental and Sales in Boston

As you can see by the pictures below of various 1200W ballasts, the Arri compact mag ballast is pretty compact but nowhere nears as small and lightweight as the two electronic ballasts. Mag ballasts also have a tendency to hum so they are best located outside the room in which you are shooting. Left: Honda EU6500is (L) Honda EX5500 ® Center: Test Set-Up w/60A Full Power Transformer. Right: P2L PFC 1200W Elec. Ballast (L), Arri Non-PFC 1200W Elec. Ballast ©, Arri 1200W Magnetic Ballast ® As you can see by the picture of the generators on the left, the Honda EU6500is is considerably smaller and lighter than the old Honda EX5500. I am going out on location for a couple of days, so I won't be able to respond to any more questions until Monday. As much as I love chatting with you guys, I gotta do that work thing to pay the bills. - Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental and Sales in Boston.

How does what compare for size, weight, and noise? - Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental & Sales in Boston

I don't necessarily agree. Magnetic HMI ballasts have always incorporated some Power Factor Correction. John might be onto something when he says: Depending on the type of filming you do, you may in fact be better served by an older magnetic ballast over a non- Power Factor Corrected electronic ballast. A 1.2kw electronic ballast draws 19amps ( verses the 13.5 amps of a magnetic ballast) so it will always trip the common 15amp house circuit and will trip a 20 Amp circuit if there is something else, like a computer or light, on the same circuit. Where you can't always know what else is on the same circuit, or even if it is a 20 or 15 Amp ciruit, a 1.2kw magnetic ballast drawing only 13.5 Amps is the safer bet since it can operate on a 15 amp circuit even with other things on the circuit. Non-Power Factor Corrected electronic ballasts are meant to be used on film sets where every circuit is 20 Amps and you know what is on the circuit because you are distributing the power yourself from a tie in or generator. If your style of shooting requires that you plug into wall outlets, you will be better served by a magnetic ballast. Left: Grid Power w/ no load has a THD of <3%. Center: Conventional AVR Power w/ no load has a THD aprox. 19% Right: Inverter Power w/ no load has a THD of aprox. 2.5%. But that is not the only benefit to using a magnetic ballast over a non-PFC electronic ballasts. If you don’t have access to the newest PFC electronic ballasts, the older magnetic ballasts are in fact cleaner running on portable gas generators than non-PFC electronic ballasts. As mentioned above the harmonic distortion created by non-PFC ballasts reacting poorly with the distorted power waveform of conventional AVR generators limited the number of HMIs you could power on a portable generator. The primary factors limiting the use of HMIs on portable generators has been the inefficient use of power by non_PFC electronic ballasts and the harmonic noise they throw back into the power stream. The adverse effects of this harmonic noise (evident in the oscilloscope shots below), can take the form of overheating and failing equipment, efficiency losses, circuit breaker trips, excessive current on the neutral wire, and instability of the generator’s voltage and frequency. For these reasons it has never been possible to operate more than a couple of 1200W HMIs on a conventional 6500W portable gas generator. Characteristic voltage waveform of a non-PFC electronic HMI ballast on grid power (left), on power generated by a conventional AVR generator (middle), and power generated by an inverter generator (right) As is evident in the oscilloscope shots below of a 1200W magnetic HMI ballasts on grid power (left), on power generated by a conventional AVR generator (middle), and power generated by an inverter generator (right), the lagging power factor caused by the inductive reactance of magnetic ballasts has by comparison only a moderately adverse effect on the power waveform. Outside of causing a voltage spike in the inverter power, magnetic ballasts actually show a positive effect on the already distorted power waveform of the Honda EX5500 conventional generator. For this reason magnetic ballasts work better on conventional generators with frequency governors than do non-PFC electronic square wave HMI ballasts. Characteristic voltage waveform of a 1200W magnetic HMI ballast on grid power (left), on power generated by a conventional AVR generator (middle), and power generated by an inverter generator (right) These oscilloscope shots show that if you don’t have access to the newest PFC electronic ballasts, the older magnetic ballasts are in fact cleaner running on portable gas generators than non-PFC electronic ballasts. And, where inverter generators like the Honda EU6500is do not require crystal governors to run at precisely 60Hz, you can operate magnetic HMI ballasts reliably on them. In addition, the smaller magnetic ballasts (575-2500W) offer the distinct advantage of being less expensive and draw less power (once they have come up to speed) than the commonly available non-PFC electronic equivalents (13.5A versus 19A for a 1.2kw.) Of course there are downsides to using magnetic ballasts. One down side is that you are restricted to using only the safe frame rates and shutter angles. But, when you consider that every film made up to the early 1990s were made with magnetic HMI ballasts you can see that being limited to the safe frame rates is not all that restrictive. Another downside to magnetic ballasts is that you can’t load the generator to full capacity because you must leave “head room” for their higher front end striking load. When choosing HMIs to run off portable generators, bear in mind that magnetic ballasts draw more current during the striking phase and then they “settle down” and require less power to maintain the HMI Arc. By contrast, an electronic ballasts “ramps up”. That is, its’ current draw gradually builds until it “tops off.” If it sounds like I’m hyping the Honda EU6500is generator, it is not because I rent or sell them. As a Gaffer of a lot of tight budgeted independent shorts, I think these machines are a major development in portable power. Since magnetic HMI ballasts will operate flicker free at all standard frame rates on them (without the need for a crystal governor), inverter generators like the Honda EU6500is give new production life to older 2.5kw & 4kw HMIs with 120V magnetic ballasts. - Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental & Sales in Boston