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Brian Doran

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About Brian Doran

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  • Occupation
    Industry Rep
  • Location
    New York
  • Specialties
    ARRI Lighting Technician

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  1. Is the buzzing constant, or does the head buzz briefly and then go quiet, failing to strike the lamp?
  2. Yeah, it looks like they specify two 14.4v V-mount batteries.
  3. Absolutely agree in regards to testing and being aware of line-loss for tungsten loads. I just want to add that although electronic ballasts can regulate the mains voltage and their output voltage, you can still incur line-loss across your run of header cable. Trying to use a single 100' run instead of two 50's, metering out your header to find any high resistance wires, and keeping clean contacts can all help keep resistance and thus line-loss down. The newer ARRI ballasts now use CCL (compensation for cable loss) circuitry, wherein a feedback circuit in the head is telling the ballast how much extra voltage is needed to overcome the line-loss. helps keep things predictable.
  4. Why not just use the TM30-18 Rf scores? With 100 color samples and a very intuitive graphic showing color gamut as well as shift, I think it's pretty hard to beat. It is based on the standard human observer, much like CRI, which can be an issue, but it certainly gives us more information with more data points and is thus harder to cheat. As far as I know, TLCI is based on CCD sensors, so it might not be an accurate predictor of CMOS sensor characteristics. SSI is the only one of the three with a real advantage, being that one can easily change the reference source if they want to match non-Planckian sources like gelled lights or fluorescents.
  5. If it's anything like the old ARRISUN 12, then you cannot use the modern G38 single-ended HMI lamps, no. The sealed-PAR lamp had its own reflector, so our old ARRISUN did not have or need one. Running a lamp without this built-in reflector would likely cause overheating and damage to the fixture, as much more heat would be absorbed by the inner baffle than was planned in the design. More troubling, is the lack of UV filtering glass on the fixture, again due to the sealed-PAR's inclusion of UV filtering. This is all based on my experience with the old ARRI heads, if the Desisti heads were different, please don't hesitate to correct me. As for sourcing lamps, I find them to be rare enough that lamp failure is often reason to scrap the entire fixture. If anyone has a source, please let me know!
  6. This is just my gut feeling, but wouldn't having a focusing lens on each LED cause multiple shadow issues? A diffusion plane is really helpful for homogenizing the multiple light sources into "one" source.
  7. That is a magnetic ballast. Like Phil said, you will have to be sure to synchronize with your camera to avoid flickering, and will not be able to dim the fixture, etc.
  8. That head hasn't been manufactured in 10 years or so, if memory serves. How does the reflector look? A bit of burnt-in dust and dirt over the years can easily decrease intensity by 20%. Though that wouldn't account for the increase you measure in spot. Perhaps the reflector has become misshapen.
  9. Are you referring to the rate of falloff here?
  10. I'm not sure that this logic holds up. Peak photopic sensitivity is defined as being 555nm, which is a green color. Check out this luminous efficacy chart. Maybe I'm misreading, but it also feels like you are referring to blue light as being longer in wavelength, while the inverse is true. If anything, our scotopic vision is more sensitive to blue light than our photopic. Please let me know if I'm misinterpreting your post.
  11. It seems to me that there is a disconnect between the terms used to describe the emotional evocation of different sources, and the technical terms used by researchers. I could imagine feeling a soft, intimate emotional response to fire light, and this response would be taking place in between my eye's observation and my brain processing that information. And that is not to say that it is invalid or that my brain tricking me, photometry is the study of how the human eye perceives light, and that eye/observer is just as important as the photons of light. That's one of the interesting things about color, it can be greatly informed by our memories and feelings. One might observe an orange to be of a greater saturation if that is what they remember as a child, etc. Balancing this real and justified emotional interpretation of light/color with the technical aspects is a challenge that the DP, LD, or gaffer must face. As someone on the manufacturing side, I appreciate that the artistry of light may take on a different vocabulary and way of thinking. However, we work to create tools that best suite your needs, so maintaining a dialogue and getting input from the artist is essential if we want to create something useful. Sometimes we may need to take a step back and consider what we should do because it is useful, vs. what we can do because it is possible. At the end of the day, we are creating tools, and we must use objective methods and terminology if we want repeatable results and quantifiable goals. I'm not saying that we don't want to hear the artistic terminology, but if there are certain things that you like or dislike, digging into the technical language will help make our dialogue much more effective. When you say soft, perhaps there is an emotional context motivated by color or even the flickering that brings about memories of sitting around the campfire. When the R&D team designing a fixture says soft, they are referring to a diffuse source vs. a specular one. At the end of the day, our lighting instruments have to be described in purely technical terms for the sake of specifying and manufacturing; The further that you the artist can bring the conversation into the technical realm, the better the chances are that we can move the technology in a direction that suites your needs.
  12. Not a standalone library, but the Illumination Engineering Society does have a photometric .IES file extension named for them. I've used a free program called IESViewer for these files. .LDT are also used, but I haven't played around with those at all. ARRI provides both file types for their current fixtures, and I believe ETC does as well. Not the prettiest UI, but it works.
  13. That is not a light, it is an ultrasonic distance measuring device for the 1st AC. It's a bit like echolocation for bats.
  14. Not a book, but I'm quite a fan of Luke Seerveld's YouTube channel, Meet the Gaffer. He does short vlogs of various lighting setups, explaining the function of each instrument. It's a bit of a living light plot. There are also episodes dedicated to miscellaneous tips and tricks. Great stuff.
  15. I don't know the inner working of those regulated 48V DC batteries, but I don't suspect that a step-up transformer is utilized, as they're rather heavy, expensive, and are not regulated. The two batteries are likely run in series to combine their voltage, and then regulated through a boost and buck DC-DC converter. Doesn't really answer your question, but I couldn't help it. As for running an 800W HMI off of battery, the necessary warm-up time for an HMI might really chew into any operating time that the battery could supply. Short of buying or renting a voltstack, I don't know. If someone has a recommendation, I would also love to hear about it!
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