Forum archive - Video Noise and IRIS control

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Video Noise and IRIS control

video_enthusiast07 posted 2007 May 21 16:43

Hi everyone, something is bugging me.......I have been recording some footage lately in the outdoors with full daylight and then burning it to a DVD to see it for testing purposes. Typically a well lit video shouldn't go through "noise" problems, but the problem is that i do see some noise on the video, its not alot of noise but I can see it. I was told that in order to fix that and have clean video I need to adjust the IRIS manually, and not let the gain kick in. Is that true?

JohnnyMalaria posted 2007 May 21 19:12

Certainly, not applying gain and opening the iris wider will produce less noisy results. Using a slow shutter speed will, too.

video_enthusiast07 posted 2007 May 21 19:25

JohnnyMalaria : Certainly, not applying gain and opening the iris wider will produce less noisy results. Using a slow shutter speed will, too. hey, thanks for the info. :) Im still sort of a newbie, I just need to make sure on some details, I know they might sound dumb because they are probably so easy to do, but I am a newbie. when you say opening the iris, you mean pushing it up to the limit in brightness where the video still looks natural right? ...like pushing up the "F 1.4 ...and so on numbers"? and when you say applying no gain, you mean keeping it at 0dB right? or am i being confusing? because the camera has variable numbers depending where Im aiming the cam. the shutter i think i can manage, its doesnt sound that technical, its just the iris and gain that i need to work on for better results.

Cornucopia posted 2007 May 21 22:47

The "GAIN" is something that is usually only used when you've set everything else as best you can, but (barring adding more light) you STILL don't have enough light for good exposure. The variables are: SENSITIVITY (GAIN is included here, as is real pixel sensor area/size) IRIS/F.STOP SHUTTER SPEED (although this is partially mitigated by the requirements of motion capturing) LIGHT LEVEL which all combine to give you: EXPOSURE Noise is added with increase in sensitivity (especially what "artificially enhanced" with GAIN)--much like film grain size vs. sensitivity. Noise gets "AVERAGED OUT" with slower shutter speeds Scott

Steve Stepoway posted 2007 May 21 23:08

You said that you burned this to a DVD -- is it possible that the "noise" you are seeing is encoding noise (artifacts)? What bit-rate did you encode at? Steve

video_enthusiast07 posted 2007 May 21 23:10

Cornucopia : The "GAIN" is something that is usually only used when you've set everything else as best you can, but (barring adding more light) you STILL don't have enough light for good exposure. The variables are: SENSITIVITY (GAIN is included here, as is real pixel sensor area/size) IRIS/F.STOP SHUTTER SPEED (although this is partially mitigated by the requirements of motion capturing) LIGHT LEVEL which all combine to give you: EXPOSURE Noise is added with increase in sensitivity (especially what "artificially enhanced" with GAIN)--much like film grain size vs. sensitivity. Noise gets "AVERAGED OUT" with slower shutter speeds Scott Thanks :)

video_enthusiast07 posted 2007 May 21 23:12

Steve Stepoway : You said that you burned this to a DVD -- is it possible that the "noise" you are seeing is encoding noise (artifacts)? What bit-rate did you encode at? Steve Hi Steve, this is what i do..... when i transfer the video from the camera to the computer I use Pinnacle Studio, Full DV transfer. Then i use DVDit Pro to burn it on a DVD, I use the highest quality slow transcoding method to get better results, Im not sure what the bitrate is on that, but almost certain its 8000kbps.

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