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

Started Apr 10, 2013 | Discussions thread
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Steen Bay
Veteran MemberPosts: 6,792
Re: Return of Interesting article on DxO about 5D III and D800...
In reply to qianp2k, Apr 13, 2013

qianp2k wrote:

KLO82 wrote:

Steen Bay wrote:

qianp2k wrote:

Steen Bay wrote:

aftab wrote:

Now, let us look at scenario B and scenario C again. In both cases A looks sharper than B. What does that mean? More resolution = more sharpness. That is resolution = sharpness in this two scenarios. And almost all scenarios are like this. So, we can actually use the terms resolution and sharpness interchangeably.

But if comparing for example the 12.7mp 5D vs. the 18mp 7D, then things get a bit more complicated, because it seems that 5D (most often, with most lenses) has the best sharpness (MTF-50?),


while the 7D has the highest resolution (MTF-10 or MTF-5?).

Not necessarily. Actually with most  EF lenses 5D outresolves 7D if you frame them in the same AOV (as tested by DXOMark in either old MTF or new P-MPix unit that are two different expressing units but with the same result). Only very few lenses such as with 300L/2.8 IS II 7D/60D outresolves 5D.

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But what if we could compare the MTF-10 er MTF-5 values (which we unfortunately can't anymore)? Then I think that the 7D would win, because it has quite a bit more MPs.

This is what you are talking about:

In the 2nd pic, I was supposed to highlight the MTF 20, but instead wrongly circled the MTF 30. Dxo used MTF 20 as resolution ("critical" resoltion or something like that. I cant remember the exact term).

Thanks for saving the snapshots of old DXOMark test in MTF unit before DXO changed to P-MPix unit.  Regardless of what unit DXOMark used, it shows the same clear result.  So P-MPix should not be an excuse for those deny/challenge DXOMark tests as from what I have seen and remembered the test comparison results are consistent with former MTF and the latter P-MPix.

Yes, thanks to KLO82 for that.

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.

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