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Richard Andrewski

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    Industry Rep
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    Shenzhen, China
  • Specialties
    Lighting, videography

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    http://www.coollights.biz
  1. Of course, there are high and low CRI MH bulbs and the higher ones will have less apparent green spike. There are many architectural and "entertainment" MH bulbs for example that are very suitable for film/television use. I haven't seen much evidence that if there is an apparent green spike that it diminishes. Of course any green spike that's there is more a problem on real film than on digital. Don't know about the terminator films but that's interesting if true.
  2. Thanks for your comments Phil. If you get a softbox, you may want to pick up a SPOT version, you will find the softbox works better with them as they are stronger. What are those two large round lights in the 2nd picture? Just curious.
  3. A lot of people think so: http://www.dvinfo.net/forum/photon-management/467508-my-cool-lights-experience.html http://www.reduser.net/forum/showthread.php?t=36727 http://www.dvxuser.com/V6/showthread.php?t=213548 http://www.dvxuser.com/V6/showthread.php?t=147772
  4. Thats a pretty ingenious idea but all these types of panels with matrices of LEDs are still multiple sources and even one that's called a "spot" (i.e. used LEDs with a more narrow beam angle) is still basically a very narrow flood light. All they are doing in a model like that is having two types of beam angle LEDs on the same panel and fading between them with a dimmer that crossfades from one set to the other. Someone said if you could just crowd all the LEDs together than would make something more approximating a "hard" source just doesn't work. Its still a bunch of small sources and you still have shadow issues. We just don't know how to make something simulating a single, powerful HMI or tungsten fresnel yet.
  5. Hi JD, Its not just that its a big source, its that its multiple sources too. Because an LED panel made up of 5mm LEDs is a far harder light than a flo. Each LED by itself is too weak to do much other than be an "indicator" or some other similar function. Form a matrix of them however and you have something that's kind of a cross between a hard and soft light. Just like with an LCD screen where 1 pixel wouldn't do us much good. The collection or matrix of them together forms a very usable tool. The only real way to get good projection and "shadow rendering" as I call it is with a point light source like a tungsten or HMI bulb. And its helpful to have focusing capability so putting that bulb in front of a mirror and behind a good lens like in a fresnel is invaluable to allow beam shaping, gel color projection and of course pattern projection like gobos, cookies, etc. You can't even do that with a flo because as we know its shadow rendering capabilities are also weak with vaguely defined shadows. Till we can find a single LED that can function as such a point light source, its going to be a while before an LED fixture can totally replace a fresnel. That doesn't mean the LED matrix fixture is unusable and doesn't have its applications, because it does. In fact, it can do some of the things you might do with a flo but even better, with greater power efficiency and easy and smaller battery operation than you could do with a flo or hmi. So all these tools still have their place and as the previous person said, you can't replace everything with one light.
  6. Yes you will. A lot of people don't understand or believe it but there is an explanation. Most filters of any kind reduce the output of what they're filtering. Light waves as well as sound waves. Listen to your stereo with the bass turned up. Those eq knobs are filters for adding or subtracting frequencies in a simplified way of explaining it. Turn just the bass down thus filtering out low frequencies. You may find yourself reaching for the volume knob to make up for the frequencies being filtered that gave the sound more "volume" or at least perception of volume. Same with electronic light such as flos or hmi. They lose a lot of volume or perceived volume when the peak area is filtered in the name of higher CRI. When a tube manufacturer manufactures a higher CRI product, they in essence add more magenta to the phosphors used in the tube. This is no less of a filter than if you added minus green gel to the outside of the tube. Thus since the green spike is what really gives the light its efficiency, you lose light. Kino simply "turned up the volume" so-to-speak by driving the bulbs harder to replace the lost light of a higher CRI tube and 95 is realistically about as high as you're going to get anyway. Hope that helps.
  7. It puts out more light precisely because the CRI is lower. Given the same type tube, wattage and all other factors being equal (including the ballast being the same type and power factor thats driving both high and low cri tubes), the lower CRI tube will always be higher in lumen output. Its simply because the green spike which is not appreciated in filmmaking is well appreciated in the lighting world for the extra "umph" it provides to electronic lighting from fluorescent to metal halide and even now to LEDs. Kinoflo got around this issue by simply overdriving the tubes to try to win back the lost lumens when the CRI was made higher.
  8. They're a lot of trouble and require special isolation to use with some kinds of electronic lighting. Here's a link about it: http://www.reduser.net/forum/showthread.php?t=20673 More: http://www.tvss.net/pq/ballast.htm and still more: http://www.physicsforums.com/archive/index.php/t-174420.html I guess if you have an isolation transformer on the input to your fixtures you won't have a problem.
  9. I think I mentioned somewhere recently in a post on here about HMI bulbs that they're used in follow spots a lot these days. Well the Xenon bulbs are getting quite a bit of use for that too. They have a much higher lumen per watt rating than HMI bulbs so more efficient. When you see the huge moving beams cutting into the night at some place in your city (like a night club or whatever trying to attract people there), its generally a Xenon these days. So powerful, they're used in a lot of military lights too. Like this surplus tank light that some hobbyists snap up: http://www.candlepowerforums.com/vb/showthread.php?t=92396 They're super efficient and create an incredible beam. We've looked at a lot of the 35w type bulbs which are also used in HID flashlights. The ballasts are super simple and can be very small. Nothing great just yet but you never know what you'll stumble across in research. We've also tried some high wattage LEDs from 30w to 100w (there are even 300w ones now) but the issue with those is they need super large and heavy heat sinks so they aren't very suitable for small and portable lighting. CRI is an issue in most of those also and they are mostly used for street lights these days. Luxim is making an interesting "plasma" type bulb with a high CRI but so far the unit comes sealed in a very large package that includes a solid state bulb and ballast with a fan so thats not a very usable unit yet either for film/tv lighting. We're always on the lookout though.
  10. Yes indeed, a real bonified Xenon car 35w 6000K headlight. Back in 2007 I was experimenting with some 35w hid bulbs of various kinds for use in a small pepper fresnel (equivalent in size and output to something like an Arri 150 tungsten but only using 35w power) to complete our "CDM" line of fresnels. They all had the common problem of low CRI. As Karel points out you can color correct it out if thats all you're using. Most of the time though, you don't have the luxury of using only one light for everything. Real daylight streaming in the window, etc. That's where you get in trouble with these low CRI types. They would be acceptable however with a bit of minus green but I was holding out for some other low watt / high power output technology where the CRI was a bit higher. In reality, it would be just fine for most things you use a pepper fresnel for like back / rim / hair lighting but I don't want to fight customer perceptions so we'll wait for a better solution before we do the lowest wattage model in the CDM line.
  11. Sure you can tweak it because it was the only light shining on the color chart in both cases so its easily controllable just like white balance could have taken out the green too. Thats not the point. The point is that the CRI 87 light is easily mixed with real daylight and there won't be any grainy / gritty issues in the pictures taken with it. The CRI 60 on the other hand, if mixed with daylight or another kind of light will create a mishmash that may not be so easily be sorted out. The chart may not be vibrant because of the angles I was shining the light on it. If I had bounced the light off a white bounce card, it might have been more uniform. It may also be a bit overexposed too. Take on different days with different cameras.
  12. We've done some work with HID / metal halide bulbs in some fixture with great success and there's a guy somewhere in Australia named Bob Grant that had made some China lanterns with HID bulbs in them. I would recommend a G12 base single ended 150w metal halide as something thats more easily controllable, there is a good choice of electronic ballasts that can drive it and not a bad selection of color temperatures including some up in the bluer ranges for the look you want. And also small enough and low enough wattage that it shouldn't bother your paper lantern. We like those bulbs a lot.
  13. There's all kinds and grades of "hmi" bulbs although the one you showed is not an HMI bulb. Only Osram's HMI (it's their brand name and doesn't mean anything else) is an HMI, everything else is an HMI compatible technically. The particular bulb you showed would be for use in follow spots, theatrical lighting, some architectural lighting and especially follow spots, hence the 7200K color to make the spot pop out all that much more from the other lighting. The CRI is more than high enough for those uses nor do they care about 5600K/6000K being a standard. And that's also why its not a hot restart kind which is why its not a true HMI compatible--hot restart is one of the major criteria for whether its a full compatible bulb or not. It will most assuredly operate off the same HMI ballasts but you wouldn't want to try and relight it before about 5 or 6 minutes after it was turned off. The horrible screeching sound tells you its not a good idea and its best to shut off the ballast right now. As far as CRI goes, the lower CRIs will manifest themselves as an abundance of green when using discharge lighting like fluorescent or HMI and even many lesser expensive LEDs in an image taken that was lit with the offending light. Actually CRI 80 is not all that bad especially in digital mediums where custom white balance can take care of any issues in many cases. It really starts to get bad below that and white balance can have a tougher time working on it. Especially when other kinds of light get mixed in. It really gets confused at that point and the results can be nasty. I've posted an example color chart I took of a Xenon light I have thats about CRI 60 to give an idea of what that can look like. This is just camera white balance at 5600K, no custom white balance. Needless to say, that one isn't much use for anything other than as a back or rim light. For comparison sake, here's one taken with a Cool Lights CRI 87ish fluorescent tube As for how CRI is really measured by manufacturers, we use something called an integrating sphere which is a kind of isolation chamber hooked up to a spectroradiometric computer: And that gives you an accurate reading from 1 to 100 of the CRI index. You can get a report printed out from the test session which has all the stats about the tested bulb from color temperature, lumen output and CRI among other things. Other than that, you could estimate CRI based on color charts like the ones above.
  14. Not to mention too that you may have flicker issues if you mean real mercury vapor lamps which often have very simple magnetic or cheap electronic ballasts. And you may find if the wattage is high enough and your lantern small enough, your paper lantern might burn.
  15. You can make small fixtures with larger wattage HMIs but in general its not a good idea for bulb life. You can think of the fixture as a heat sink for the bulb. The more heat sink the more the life of the bulb. So you trade off portability and size for bulb life in general is another way to say it. When you have a ballast that can drive a 575 or 1200w, its 99% the case that its two different heads you'll be driving (and not one that can do both) as its not very practical for reasons of the socket alone to do both in one head. As I said, there will usually be a subtle difference in the wiring of the cable between a 575 and the 575/1200 ballast and a 1200 and the 575/1200 ballast. This is the signal the ballast needs to know to be able to turn up or down its power to drive a 575 or 1200 bulb. Getting those signals crossed would be dangerous as we said before.
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