Jump to content

Tom Morrow

Basic Member
  • Content Count

    18
  • Joined

  • Last visited

About Tom Morrow

  • Rank

Profile Information

  • Occupation
    Gaffer
  • Location
    San Francisco
  1. My rule of thumb is to put gels on the tungsten source instead of the daylight source when trying to achieve a particular balance.
  2. Yes gels will tend to lower the cri if used on non black body sources because they are introducing further nonlinearities into the spectral response. How much this is an issue will depend on subtle interactions between the spectral response of gel source and sensor so there is no formula. If you are adding ctb onto a daylight hmi I doubt it would be an issue. But I have seen horrible results adding cto to cheap daylight LEDs that looked ok without gels as daylight. They totally didn't match tungsten at all. Also mediocre results for adding plus green to low cri daylight to match gre
  3. I have found a loose connection around the VEAM connector on my Arrisun 1200 plus head; when I wiggle the cable from the head to the connector, the HMI sometimes blinks off and tries to restart. I'm pretty sure one of the solder joints inside the connector has failed, so I'd like to take off the connector and resolder it. But I can't figure out how to disssemble the VEAM connector which looks like the left one in this pic: http://www.mldvideo.com/wms/api/image/product/2336/2286/600/600/image.jpg I can screw off the tension relief on the end but the body stays in place. It looks i
  4. Ordered a sel/xs lamp from b&h. The lamp that I received said 1200w/sel but didn't say xs anywhere on it. I suspect that the xs is not supposed to show up on the lamp. I also learned that uvs is replacing xs so the next lamp I buy will be a 1200w/sel/uvs. Uvs means lowered uv output. Anyway I now cannot reproduce the flickering issues with the old or new lamps now. I am not sure if the flicker just got burnt out or what but the flicker that was occasionally very bad is now not in evidence. I am guessing the capacitors are marginal enough that I should probably replace them bu
  5. As I read ville's post he was thinking of shooting in daylight camera balance for the flos then correcting the 3.2k incandescent (high cri means no green spike to me) on faces to white with ctb in post. I think where David was going was that just shooting with camera at incandescent balance would achieve the same effect more simply.
  6. I got an answer to my question about the different lamps: The SE designation stands for ‘single-ended’, while SEL stands for ‘single-ended lamp’. Those are just the terms used by each manufacturer to differentiate their products. The SEL/XS however does have a greater lamp life of approximately 1000 hours due to the eXtreme Seal technology to help withstand excess heat. On the other hand, the SE lamp only has a lamp life of approximately 750 hours.
  7. As I understood it, Ville was talking about shifting the talent's face with a CTB type blue shift in post. It sounds like he was using the word hue in the colloquial sense of changing the color, not the more precise way that hue means moving along the magenta-green axis to camera folks. Shifts along the Warm/Cool (Orange/Blue) axis are called changing the Color Balance, or Kelvin Shifts long the Magenta/Green axis are called changing the hue. But in art classes and computer graphics (including photoshop), Hue changes mean going around a color wheel in any direction to any destinatio
  8. Sounds like a good plan. If your scene has both green-spike flos and incandescent light, you will need to correct the green at the flo source not at the camera or post. Otherwise you will accentuate the magenta of the incandescent if correcting with minusgreen in camera or post.
  9. I see that most websites say the correct bulb for the Arrisun 1200 Plus HMI head is the Osram 1200W/SEL/XS. But the bulb that Arri recommends in their literature is the 1200W/SE, and the bulb that was in my head was marked Osram 1200W/SE, not SEL/XS. Does anyone know if the SEL/XS is the same as the SE, and if not what is the difference between the two? I sent this question to my dealer but figured perhaps someone on the net would know better.
  10. Thanks Matt. I went to my local supply house and spoke with the guy who services Arri lights. He said showed me the label of the moly lube that Arri has recomended to him and it looked like this: http://www.amazon.com/Sprayon-S00200-OZ-MOLY-LUBE/dp/B00L42R48E When I search for Sprayon S00200 I get this which I assume is the new label: http://www.sprayon.com/product-categories/industrial-lubricants/dry-film-moly-lubricant-aerosol-lu200 But he also showed me graphite powder and said that mixing it with isopropyl alcohol allows it to be applied without making too much of a me
  11. Using digital color balancing (in camera or in post) is becoming a common way of dealing with flourescent lights. In the early days most overhead flos had horrible green spikes and they were fairly consistently horrible in the same way. So a minusgreen filter was a good "one size fits all" solution. Today there are many different types of flos in use in commercial environments all with different color balances and amounts of green spikes. More and more often the green spike is becoming smaller as manufacturing techniques improve and more R&D is going into making flos look like inca
  12. I guess I can answer my own question here. I read the HMI chapter in Set Lighting Technicians Handbook, and learned that yes magnetic ballast HMIs basically rectify the 60Hz sine power into 120Hz half-sine pulses. So no the flicker is not 60Hz but there is regular flicker. As to my irregular flicker problem, I did a lot of work and I think I solved it. - Determined that the green ground wire in the outlet cable had a break in it, and replaced the cable. - Determined that someone had swapped hot for neutral in the NEMA5-15 plug so it was wired unsafely, and fixed that while replacing
  13. So here's my more general question: is it normal for HMIs to have visible ~60Hz flicker or is that a sign that the waveform going to the lamp from the mag ballast has an unusual/defective duty cycle with too wide a gap between pulses?
  14. Thanks for that. Sounds like the issues you are talking about are generally high resistance from bad connections. I will try taking the lamp out and putting it back in the socket, to see if perhaps it had a bad connection. I do note that there is some pitting on the aluminum head which leads me to think these might have been exposed to rain at some point. BTW that link doesn't work for me on iOS but I assume I can see the same thing by going to the HMI lights with Magnetic Ballasts section in http://www.screenlightandgrip.com/html/emailnewsletter_generators.html What I got o
  15. I just bought my first HMI light, a used Arrisun 1200 Plus with magnetic ballast. I am seeing flicker with my naked eye which I wasn't expecting. I am curious if others have seen the same issue. Here is the note I sent to the experienced gaffer that I purchased it from. He said the light was about 20 years old and he has owned it the whole time.... I want to ask your advice about the Arrisun 1200 HMI that I just bought from you earlier today. As soon as I fired it up in my dark apartment I noticed that it was flickering in a way that was easily visible to the naked eye. The flicke
×
×
  • Create New...