2012 February 1st, 11:09
Noisy video on low ISO - T3i
I'm stressing over a recent shoot with my new Canon T3i and would greatly appreciate any advice that might prevent this problem the next time around...
The setup was a nighttime interior in a small room, so I made sure to light the scene exceptionally well (two 500w lights, not pointed directly at the subjects but reflected off of white walls/ceiling); with this much light I was able to shoot at the lowest available ISO (100) with an aperture of (I believe) 5.6.
This looked perfect in the viewfinder, even through my magnifier, but when I brought the clip over to my editing system I was horrified to see some very noticeable video noise -- almost pixelation, really -- mostly in the darker areas of the frame (would post a clip or picture if I were at home). I had thought that by shooting at a low ISO and one of the wider apertures the kit lens offers, I could avoid noise/grain -- or, at least, obvious grain. Any ideas what might cause this? Did I still not light brightly enough? (Can't imagine that's true, considering the sensor size of this camera)?
Again, any help, opinions, advice, etc. would be VERY greatly appreciated. I'm really new to DSLR video, so if I've somehow made a stupid mistake I definitely wouldn't mind someone telling me so. Still would be better than tearing my hair out over this. Thanks!
2012 February 1st, 12:16
The culprit is underexposure in the dark areas of the frame. Underexposure at any ISO can easily result in noise, part of the answer is to not "slavishly" stay with ISO 100. Light so you get some level of adequate exposure even in the darker areas.
Don't be afraid to use ISO 400 thru 1600 if you need to. Tests I've run on night street scenes (where I can't control the lighting) showed I can use ISO 3200 and even 6400 without "objectionable" noise (I've even tested with 12,800 on the 7D, the T3i won't do that in video mode).
Another part of the equation is how you have your monitor set. One workstation I had showed awful noise, the other showed little or no noise on the same footage. The monitor on the problematic workstation was still set as it "came out of the box" with sharpness at about 90%, brightness and contrast both at about 80%. When I pulled everything down to "midpoint" and then tweaked a bit all objectionable noise was gone.
I'm talking about the settings available from the monitor controls and menu independent of the computer.
I am a "sharpness nut" and use the same workstations with Photoshop for still work, taming the monitor settings in no way affected basic image sharpness. But ANY DEGREE OF OVERSHARPENING will generate noise where little or none is present, or at the very least will make it much worse.
The T3i is an excellent motion picture tool in addition to being a more than capable still photography instrument. One of the most effective things you can do to get the most out of it in both areas is to dig in and learn basic photography (if you haven't already). Some will say: "I just want to do video, I don't care about photography much".
But the fact is that video is motion picture, which is photography with a motion component. All principles and fundamentals of photography apply in full. And the T3i in allowing you full independent control over shutter, aperture, and ISO in "motion picture" mode makes it a far more capable instrument than consumer grade camcorders we've been using for the last few yeas.
Good luck and have fun!
Last edited by Bif; 2012 February 1st at 12:24.
I am a reforming videomaking addict
2012 February 1st, 12:43
You say "pixelation" - this is very different from grain or noise, and can be seen at all ISO settings. (I have experienced "banding" even in highlights, if I need to adjust much in post.)
Did you check the histogram while setting up your shot? If everything is "crunched" together on the left side, you underexpose, and vice versa. If you need to "uncrunch" in post, you'll be increasing any compression artifacts, looking like little squares.
What contrast setting did you use? Did you use a special downloaded "style"? All these can affect the quality adversely, if you are applying them incorrectly.
2012 February 1st, 23:02
First off, I just want to say a big thanks to both of you for your thoughtful and considerate advice. Really speaks well for you and the forum overall.
I have uploaded a test clip that pretty handily illustrates the problem (particularly when blown up to 1080p): http://www.youtube.com/watch?v=y9Ryy2v6CZU
I blocked off the right side of the frame as the director is looking to keep this project under wraps for a bit, but honestly, that side isn's the problem -- it is dominated by the actors, who show no noise in their skin tones at all.
It's obvious, even with the YouTube pixelation, however, how awful the redder areas of the frame and the record player in the lower left corner look.
Bruce, I definitely see your point about underexposing areas of the frame, but in this case (and, I'm sure, others in the future), I actually intended for some areas of shadow to remain. I've seen plenty of nighttime videos with the T3i with beautiful rich blacks that contrast the correctly exposed people/objects in the frame. So, what could I have done wrong here?
Janke, I did not check the histogram or the contrast settings. The video shows what I mean by "pixelation" -- think that might still be my problem. BTW, this is completely untouched in post, no color correction or processing yet at all.
Again, I really appreciate the responses. Clearly, I have a lot to learn here -- ironically, one of the major reasons I purchased the T3i because I had shot for years on an HV20 and was unhappy with the way it handled low-light situations. Now that I've upgraded, I seem to have the same problems, which leads me to believe... It's me, not the camera.
2012 February 2nd, 03:40
What I see is compression noise (pixelation, if you wish), not sensor (ISO) noise. Of course, youtube adds its own compression...
Nice blocking out the right half; leaves a lot to the imagination!
Exposing a little lighter, and darkening in post might help a little in a case like this. Also, you could try setting the color saturation lower and choosing another picture style - but, you'd have to experiment.
2012 February 3rd, 14:06
Compression noise, eh? I see what you mean -- it seems particularly bad in the really heavily saturated red areas. Could it be that there was just (and forgive the oversimplification) too much red for those particular settings to handle? Again, I didn't view the histogram, but I assume it would have been pretty heavily weighted toward the red end of the spectrum. Didn't think such a thing would cause problems, but now I know, I guess. Anyways, thanks again.
2012 April 24th, 16:43
Originally Posted by SilentBob102
i have the same problem i tryied everything everybody said but it does not work