fluctuating white balance and/or brightness

D

Del1719

New member
I shot some green screen footage today (as I have done hundreds of times before), but when I was recording I noticed in "Onlocation" the screen was pulsating from bright to dark, not white to black, but still very notacible, and it seemed the white balance was changing as well. Everthing was set to manual on the camera, tried with mains and battery, and the footage on the card was the same as the footage captured direct to the harddisk. It was like the lights were being dimmed up and down slowly, the kights were not and did not appear to change brightness at all, anyone else had the same problem.
This was filmed at a factory that has its own power station (hydro) could it be that???, magnets etc, or is the hvx in need of an overhaul.
Derek
 
My $0.02 is that you shot under fluorescent lights. Their color temperature changes rather continuously , especially at higher shutter speeds. Its irritating as all hell for sure. You may have to re-shoot; I don't know if there is a way in post to fix that with regards for getting a good greenscreen key.
 
Hi grimrebes,
No it wasnt fluorescents, in the true sense, the lighting was those small kino flo type lights, (flicker free/ tungsten coloured but have daylight tubes as well) have had them for 18 months, and used them constantly on about 30 to 40 shoots. I like them because most of the green screen stuff I do is n sombodies office (CEO to busy to get to a studio). They are cool, so the subject dosnt start sweeting after 10 mins. I used to have redheads, but with 2400 watts shining in a small office, it soon gets warm.
It is also a very soft light, no shadows.
I think I will have to re-shoot, thank god it is not a difficult/expensive one to do, and to be honest I think I will get a better performance from my talent......was a bit nervous 1st timer. And to fix it in after effects will take longer, and not have such a good result
Will try the camera set up tonight, different light set up etc, and hope I can reproduce the effects, then can fix it, just wondered if any one else had the same problem.

Derek
 
Hi,
grimrebes: Was recording at 1080 50i (live in Norway Pal country)
Barry: I think I was at 1/120, but did try different settings at the end to see if I could correct it.
One thing I remember was it seemed to be locked on open, could not adjust ap at all????
I did have manual set and manual focus, and did a white balance at the start.
Derek
PS, Great DVD Barry, fantastic insight to what I still think is a great camera.
 
Sorry, also meant to say the pulsating takes about 1 min, from its brightest state to it dimest, and not that noticable when you watch the footage, but nightmare to key out, and because it is to go on a near white background, it stands out in the darker parts. Its a bit like the sun going in and out of the clouds every minute. Derek
 
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