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John Carrithers October 20th, 2011 11:24 PM

5D noise in gray seamless backdrop
 
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I had a shoot today. It was simple interviews in font of gray seamless. In the gray background I'm see a lot of compression noise. The ISO was around 250 f/3.5 1.30th. PP was neutral with detail and contrast turned all the way down and with the 70-200mm f/2.8 IS II.

I looked at some footage the other day of a friends shoot in front of a black background and remember remarking how clean the blacks looked. Has anyone else had this kind of artifacts in dark areas of your frame? Figured it must be an artifact of the h.264 codec but thought I'd ask since my friends footage looked so clean.

JC

Ken Diewert October 21st, 2011 11:54 AM

Re: 5D noise in gray seamless backdrop
 
Hey John,

Are you saying your shutter speed was 1/30th? If so, that would seem to add noise. I don't shoot below 1/60th. In fact I read some time back, I think it was Phil Bloom, to use 1/60th almost exclusively (or 1/50th in PAL land), and use aperture and ISO (or ND if outdoors - more light if indoors) to set exposure.

I have also heard and subscribe to the theory that ISO multiples of 160 are best for the 5D (160, 320 I've never done the testing myself but I don't hesitate to shoot (for the web) at ISO 1250.

I just found this ISO test on Vimeo that shows shows the noise at each setting. Very interesting. ISO 250 to be far noisier than ISO 320.


Chris Barcellos October 21st, 2011 12:09 PM

Re: 5D noise in gray seamless backdrop
 
Yes, shoot at ISOs 160,320,640,1250, and 2500. These will provide reduced noise over the in between ISO's.

Second, I tried a shoot one time were I under exposed in a low light situation thinking it would be better to do that, and add gain in post, than shoot in a higher ISO. That is a mistake. It results in a much noiser final image. So rule for me is expose properly, even if it means go to higher ISO. I use a Marshall monitor with false color to help achieve that.

Ben Denham October 25th, 2011 01:12 AM

Re: 5D noise in gray seamless backdrop
 
Quote:

Originally Posted by John Carrithers (Post 1690444)
I looked at some footage the other day of a friends shoot in front of a black background and remember remarking how clean the blacks looked. Has anyone else had this kind of artifacts in dark areas of your frame? Figured it must be an artifact of the h.264 codec but thought I'd ask since my friends footage looked so clean.
JC

Your friend may have crushed the blacks in post. If all of the pixel values that appear to be black are set to black with a levels adjustment your noise will disappear. For best results you would make sure as little light was hitting your black backdrop as possible and then put as much distance between your subject and the background as you can. From their your levels adjustment will be a minor tweak that won't affect the rest of the image and will give you a clean black backdrop.

I would also avoid the level of grey you have in your background. You either want black (with the slight levels or curves adjustment) or a much lighter grey (that keeps your background brighter and in the range of exposures where the sensor is at its best). As a general rule darker areas of the image will always have more apparent noise so a dark background that isn't black is an awkward in between when it comes to noise.

Noise reduction software like magic bullet denoiser or neat video can help however they will probably also smooth out the wrinkles of your subject which might end up looking a little freaky.

Nigel Barker October 25th, 2011 08:50 AM

Re: 5D noise in gray seamless backdrop
 
Quote:

Originally Posted by Chris Barcellos (Post 1690579)
Second, I tried a shoot one time were I under exposed in a low light situation thinking it would be better to do that, and add gain in post, than shoot in a higher ISO. That is a mistake. It results in a much noiser final image. So rule for me is expose properly, even if it means go to higher ISO. I use a Marshall monitor with false color to help achieve that.

Amen to that. It is far better to use ISO 3200 properly exposed than 1600 & be underexposed then have to add gain (& grain) in post.

Wayne Avanson November 4th, 2011 03:21 AM

Re: 5D noise in gray seamless backdrop
 
Something interesting I came across the other day. Watching a podcast, Robbie Carman and he said that he tests all his 5Ds and 7Ds to find out what the best ISOs are for each of them.

I've always used the multiples of 160 myself, but was interested to hear that Robbie says each of his cameras are different so he has a table of which ISOs to use on which of his cameras, to get the cleanest shots.

Interesting.


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