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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. 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.
  2. 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.
  3. Are you referring to the rate of falloff here?
  4. 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.
  5. 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.
  6. 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.
  7. That is not a light, it is an ultrasonic distance measuring device for the 1st AC. It's a bit like echolocation for bats.
  8. 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.
  9. 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!
  10. The standard ARRI 2.5/4K ballast with ALF draws between 37A and 52A at 90-125V. For information, the manual is available online, here.
  11. Unfortunately, a gel can only selectively block or transmit the color that is present in the original light source. You could probably use a full stop CTO, but the color rendition would almost certainly be worse than a native 3200 LED or real tungsten fixture.
  12. The Gemini has a beam angle of 93° compared to the Skypanel's beam angle of 105°, a difference of about 11%. At 5600°K from 10 ft, the Gemini puts out 97 foot-candles compared to the Skypanel's 111 foot-candles, a difference of about 13%. At 3200°K from 10 ft, the Gemini puts out 82 foot-candles compared to the Skypanel's 113 foot-candles, a difference of about 27%. This information is pulled from the Gemini data sheet on Litepanel's website, and from ARRI's Photometric app.
  13. Hi David, You mention frequencies is the 1000Hz plus range, is the intent to use the Skypanels for high-speed photography? I'm sure you're already aware of it, but I would certainly recommend using the dedicated high-speed mode.
  14. Hi Phil, I think it's necessary for us to know more about the head before a determination can be made. If we could track down a wiring diagram for both items, that would be ideal. I worry there could be differences in safety loop circuitry. Brian
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