Dark frame, 5DIII, 6D, 70D (and D600)

Started Oct 2, 2013 | Discussions
aftab
aftab Forum Pro • Posts: 10,122
Dark frame, 5DIII, 6D, 70D (and D600)
2

Never imagined shooting the back of a lens cap in my life. But a thread in another Canon forum made me curious.

http://www.dpreview.com/forums/thread/3553005

So, I thought let me try as I own few Canon cameras. I wanted to see if Canon made any progress with regard to banding.

I don't own 70D, I downloaded 70D RAW image from a link provided in the above thread. Then I did the unimaginable. I shot the back of a lens cap with 5DIII and 6D, both RAW, both f/5.6, both ISO 100, 5DIII 1/8000 and 6D 1/4000. I opened all RAW files in ACR and set exposure to +5. All other adjustment sliders set to 0. Each picture down-sampled to 1500pix. This is the result.

6D and 70D still has faint banding (if you push +5 exposure), but compared to 5DIII it is much less and not as sharp (so less attention seeking). Vertical banding is virtually gone in 6D and 70D, horizontal banding is less too. I couldn't tell the difference between 6D and 70D. Maybe 70D slightly better?

Then just out of curiosity I decided to shoot the back of a Nikon lens cap with my D600 ( ISO 100, f/5.6 and 1/4000). I am not sure that I understand the result. Clever people here probably will.

After pushing exposure to +5 the image remained virtually as black. As if I didn't do anything. Then I adjusted the brightness in CS6 to closely match those of Canon cameras.

At this point it seemed that D600 has more banding than 6D, at least they were sharper, so more noticeable. Here is an example from the red channel of both cameras where banding is more clearly visible.

I looked at the histogram in Rawdigger too.

Okay, it seems that D600 has less information (less noise), but why is it less bright?

I don't know. Anyways, Canon doesn't seem to be the sole distributor of pattern noise if you look deep enough and its latest cameras are probably slightly better in this respect compared to D600.

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 aftab's gear list:aftab's gear list
Canon G1 X II Panasonic FZ1000 Canon EOS 5D Canon EOS 5D Mark III Nikon D600 +23 more
Canon EOS 5D Mark III Canon EOS 6D Canon EOS 70D Nikon D600
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Plastek Contributing Member • Posts: 619
Re: Dark frame, 5DIII, 6D, 70D (and D600)
3

Nikon cuts-off a portion of the signal. That's why darks are always black in Nikon.

Basically they process an image with software before saving it into the RAW file. As Nikonians say: "they cut off portion of the signal with noise".

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