Return of Interesting article on DxO about 5D III and D800...

Started Apr 10, 2013 | Discussions thread
aftab
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Re: Return of Interesting article on DxO about 5D III and D800...
In reply to Just another Canon shooter, Apr 14, 2013

Just another Canon shooter wrote:

Steen Bay wrote:

qianp2k wrote:

With one of the best lenses 100L, we can see both systems are very close but 5D still edges out a little bit.

With a bit lesser lens 85/1.8 (still very good lens), 5D leads wider.  With further inferior lenses, then 5D will further widen the lead.  The result is clear as we have seen from tons of real world photos from respective cameras.

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We can also see that the 7D actually has a higher resolution. The 5D's MTF curve stops at app. 61 lp/mm because it runs out of vertical pixels (app. 61 lp/mm represents the 5D's Nyquist frequency), while the 7D's MTF curve continues to app. 72 lp/mm (on 24 x36mm). The contrast is rather low, but the 7D's resolution is nevertheless higher.

As I said in another thread a few weeks ago, the extinct resolution of the 7D is higher but that is at a very low contrast. In most of the contrast range, the 5D is either equal (despite having less pixels), or wins easily. I am not sure why this should be surprising to anybody. The  crop penalty is real, and the (low) mp penalty is real, too.

Fair assessment. I was actually expecting the results to be much closer, especially with 85/1.8. As far as I can remember Canon publishes their MTF data measuring 10 and 30 line pairs, 10 being a good indicator of microcontrast and 30 of resolution. I have read somewhere that human eye can resolve up to 36 line pairs per mm. That's a lot if you think about it. For most people it is going to be between 20 and 30. For the argument's sake if we take 60 line pairs and bring MTF down to 20 5D still wins over 7D. What that means in terms of viewing or perception is that 5D images will appear to have more resolution because discernible (to human eye) detail will have more contrast. They probably can be sharpened better with more pleasant results in the post too.

BTW, the real test should be at equivalent FL and equivalent f-stops with common lenses. The 5D will win by even more from MTF20 up, until you get to diffraction limited apertures. The 7D will still be able to show some measurable contrast behind the 5D Nyquist frequency.

When you go to high ISO, even to high equivalent ISOs, the advantage of the 7D will be buried in the noise. On the other hand, the 5D is noisier with equivalent ISOs.

Another observation is that DXO (now) shows the 5D to be clearly the winner in the 85/1.8 case. You can reverse engineer this to make the educated guess that their P-mpix score is weighed more towards medium contrast performance.

I was thinking the same. They probably are measuring 20 to 30 line pairs down to MTF 20.

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 aftab's gear list:aftab's gear list
Canon PowerShot G1 X II Panasonic Lumix DMC-FZ1000 Canon EOS 5D Mark III Nikon D600 Canon EOS 7D Mark II +2 more
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