Incandescant Flickering

S

stevekhart

Member
I shot this yesterday in the studio using only Arri fresnels for lighting on my Nikon D90 (wb = Incandescant, F2.8), only other light is some ambient daylight. Any ideas on what's causing the flickering that is particularly obvious in the first 5 seconds of the film and how I might try and remove it with AE?

http://www.vimeo.com/17172027

Thanks, Steve.
 
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Was it visible to the eye or just the camera. Seems odd, by nature tungsten/incandescant should not flicker as the element glows. However, if dimmed way down i suppose it may possibly pulse a bit. This looks like what you are seeing. Just a shot in the dark? No pun intended. Try to recreate it. If it is the light you should be able to see it with your eye, unlike HMI flicker.
 
Thanks for looking Paul, it wasn't visible to the eye but you could see it on the monitor in LV mode. I had about 6 lights on the set, not sure that any one in particular was adding to the effect and none were through dimmers. I was hoping it was a known 60Hz lighting "feature" with the D90!
 
sorry to be a bit blunt but have you guys been living under a rock the past two years? :-) this is a well known phenomenon and the rolling shutter means even the very slight flicker of glowing light sources causes flicker/roll. this said it shouldn't really happen with 60 hz lights, but the faster the shutter the more likely. with 50 hz lights it's a major pain.
 
Thanks, that's what I needed to know, hadn't seen the connection between incandescants and the rolling shutter problem, is it something I can fix in post-proc?
 
Are you sure there isn't a fluro as well in frame on the left? It looks like the moving bands you get when your shutter speed matches the frequency that you power grid oscilllates at.
Are you in the UK (60Hz)? Were you shooting at s1/60 with a regular household fluro lamp lighting up the left wall?
 
Absolutely, the only flouro's I have in the studio are the house lights and they are definitely off during this shoot. On the left hand of the frame you can see two 300's each gelled orange glowing thru the lamp shade. Bouncing off and through the paper screen on the back wall is a 2k and there's a 650 shining through the right hand paper screen. Also on set is a couple more 650's and 300's and an 800 redhead thru a softbox and another 2k bouncing off the ceiling. And that's it!
 
with a rolling shutter it doesn't help to turn off flos, incandescents flicker too, in fact flos on hf ballasts are the only sure way of avoiding this flicker without manual control of shutter speed.
 
most canon models have manual settings, so do the gh1 and the d7000 (d3s too i think). with the d90 you just move the camera slightly until the flicker goes away, after some practice it's easy. we did a feature on the d90 with 50hz lights, and in the end this was actually an advantage since it meant we could easily keep the shutter at 1/50 throughout the film. with 60hz lights there are so many speeds that work and so you'll get different amounts of motion blur in different takes.
 
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