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Big Problem, Need Help Fast
We are renting a Varicam for a shoot this weekend and into early next week. The shoot calls for a few shots where the scene is completely dark and then is lit briefly by the sparking of an arc welder. Our problem is that when we turn off the lights, the picture fills with an insane amount of noise, almost as if the gain were on, but it isnt. When we turn the lights back on, the noise disapears. Is there some type of auto gain option somewhere that is kicking in?
As it stands right now we cannot use this camera for this shot that is vital to the project.
Is there a setting I’ve missed somewhere? I’ve gone through every menu I can think of, and have read the manual through twice and I can’t figure out for the life of me what the heck is going on.
We have used this same varicam for 4 other projects in the past and have never seen anything like this, although this is the only shot we’ve attempted like this with this cam. Has anyone seen anything like this before out of a varicam?-Ethan
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6 Replies
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Ethan,
This is a new one on me, but I’ve haven’t done siuch a shot with my Varicams. I’d say, don’t worry about; if the noise is really being recorded in the “black” just replace the blackness with clean black in post!
The Varicam is a noisy camera per se.
My guess is that you’re looking at the picture on an LCD screen, am I right? If so they are inherently noisy themselves.
Really, go ahead and shoot the scene and “fix’ the black in post.
Regards,
JS
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Is the image on the monitor noisy when you close the iris? The Varicam has no internal gain. Noise in the blacks can be greatly reduced by using a propper set up.
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Is the image on the monitor noisy when you close the iris? The Varicam has no internal gain. Noise in the blacks can be greatly reduced by using a propper set up.
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If the monitor is in the same room as the lights are when you turn the lights off you’ll see more grain.
Move the monitor or shroud it in black and see if it still happens.
Otherwise there is no internal circuit that should do what you descibe.
Remove cover and reseat boards
Record the shot and replay with lights on to see if it going to tape and isn’t a monitoring issue.Mike Brennan
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Ethan:
As the other posters have explained, there is no AGC function in the camera, thus the “gain” is not changing. What I suspect you’re seeing is actualy your eye / brain adjusting to the dark, it’s your human brain AGC / auto contrast cutting in.
Thus before you remove boards etc ( please don’t..) try this: Shoot a minute or two of footage in the dark (welding or whatever), then without changing any settings shoot a minute of footage in normal lighting, then again without changing anything simply cap the camera and roll for another minute. Examine the black level noise of the camera on all three clips, it should not change. It’s best to use a scope to really measure the noise. About the only possible way the camera can increase the noise (albeit by a small factor) is if the level dependance adustment for detail is miss set. To test for this, simply turn off the detail completely. (Film Menu #1, CAM SETTING, DETAIL to OFF)
Good luck
Steve Mahrer (Panasonic Bradcast)
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Ethan,
What is the brand and model number of the monitor you are using when the problem occurs.
Is it an LCD or CRT monitor? Have you compared another monitor with the one which displays the problem? Part of your testing should be comparing and contrasting two different units against each other to verify if one or both display the same problem.
I have had a similar issue with major noise in the blacks but the problem turned out not to be with the camera but the monitor instead. Rather than speculate let me know the info on the monitor.
Are you subrenting the gear? If so have you spoken to the engineering department at the rental house or the owner of the gear?
Tony Salgado
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