20MP vs. 20MP - comparing my 6D vs. 70D:

Started Nov 9, 2013 | Discussions thread
qianp2k
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Re: 20MP vs. 20MP - comparing my 6D vs. 70D:
In reply to Rick Knepper, Nov 11, 2013

Rick Knepper wrote:

qianp2k wrote:

Just another Canon shooter wrote:

Rick Knepper wrote:

Unless there is a significant factor(s) obliterating detail, the 70D should resolve more detail (not always the most important aspect of IQ to a given photographer). Do you have any side by sides?

How about TDP? 50L at f/1.2 on crop vs. the cheapo 85/1.8 at f/2 on FF?

DXO 85/1.8 on 6D vs 50L/1.2 on 70D 16 vs 12 mpix.

No doubt a cheaper EF lens on FF beats a very expensive lens on APS-C. However those EF lenses are not designed for crop. A more meaningful comparison should compare to native APS-C lenses designed and optimized for APS-C bodies but Canon doesn't offer such lenses (only very few EF-S lenses). For example EF-M 22/2.0 STM pancake on EOS-M (that should have similar sensor as of 70D from perspective of IQ, 70D is only slightly better) has amazing 13 mpix.

Due to much bigger sensor size and 1.6x times less pixel magnification, 6D is naturally sharper with better color tonality that becomes noticeably when view in large size.

The reason I responded as I did is because the OP used the term "detail". I think it has been proved several times on the forum with crop vs FF side by sides that more pixels in a higher density procudes more detail. Unfortunately, I didn't bookmark those posts. I proved it with a 21 MP vs 36 MP FF side by side comparison using the same lens although there were still deniers galore.

All major labs tested system (lens+sensor) in the same AOV that why DPR Lab uses 50mm lens on APS-C while uses 85mm lens on FF cameras as they have similar AOV. DXO Lab adjusts distance with the same FL lens when tested on different crop formats.

Sharpness and other apsects of IQ are a different matter from detail IMO. If it were possible to find a FF sensor with the same pixel density of a crop, and find exact equivalent lenses, I would expect the same level of detail to be captured by both but the overall clarity of the FF image would be superior due to its lower inherent noise and other factors.

http://www.normankoren.com/Tutorials/MTF.html

http://www.imatest.com/docs/sharpness/

The above two links help to understand the subtle difference between MTF resolution and sharpness. What MTF resolution we are talking about, MTF 50 or MTF 15? I believe OP tested between two cameras in the same or similar AOV with different FL lenses or from different distances. If at the same AOV (which means 6D is 1.6x closer to the subject than 70D), then 6D not only is sharper but also resolves more. If both cameras shoot from the same distance with the same FL lens that will result two different AOV photos that 6D is much wider than 70D's one. In this case, 6D with the same FL lens will be still sharper and 70D will absolutely resolve more if you crop 6D's photo on a subject (such as a bird) to the same AOV of 70D.

I wonder about the approach of Canon and Nikon to their crop cameras in view of the assertion by many many forum members that crop cameras require better lenses. (Not sure how a lens gets past the noise issue.) But, IMO, the most important thing to know about crop is that it is the budget DSLR camera in the line-up. Creating a line of extra-performing lenses seems to go counter to the general marketing effort so I do not expect better EF-S lens to ever happen. Supposedly, Nikon has a pro crop called the D300 but to my knowledge, Nikon never introduced lenses "appropriate" for the moniker.

Yes when tested in the same AOV, crop cameras with similar amount of MP will require much better lenses that natively designed and optimized on the crop format to overcome penalty from extra pixel magnification. More pixels always means more paper resolution, 41mp from Nokia cellphone camera is 41mp. The issue is it has large portion falls below MTF 15 in extremely low contrast (buried in huge amount of noise/grain) that human eyes simply unable to resolve. As in your tests between 5DIII and D800 with respective Canon and Nikon's 24-70/2.8 zoom, we can see Canon photo is sharper especially in edges (that reflected in higher DXO p-mpix test that likely calculated on MTF 50 data) but D800E manages to resolve a bit more especially in center area. By upsampling 5DIII file to D800E size, the resolution gap is a bit smaller but 5DIII also loses a bit of sharpness in upsampling.

above set at respective wide-open

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Rick Knepper, photographer, non-professional, shooting for pleasure, check my profile for gear list and philosophy. Just say NO! to MAIL-IN REBATES.

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