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

Started Apr 10, 2013 | Discussions thread
qianp2k
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Re: not sharpness
In reply to Steen Bay, Apr 11, 2013

Steen Bay wrote:

qianp2k wrote:

Steen Bay wrote:

qianp2k wrote:

The key factor is that no such lens ever existed or ever can be designed and manufactured as long as we still stay in glass lens that can fully resolve 41mp from the sensor. Even there is such perfect zero-lost lens ever existed, 41mp from Nokia 808 still will not be real 41mp after deduction from huge crop enlargement. It would resolve far less than 36mp D800, 22mp 5D3 or even will not resolve more than 12.8mp 5Dc.  Don’t forget crop penalty.

That's why I said there is simply no such sensor resolution as it has to go thru lens and has to face crop enlargement and crop penalty (FF also has crop penalty but just less and MF has much lesser).

There isn't any 'crop penalty' if the lens' image circle matches the sensor size. A lens designed for e.g. a 2/3" (4x crop) sensor can resolve much more lp/mm than any FF lens. If we take for example a 5D3 + 24-70/2.8L II and downscale the whole system by factor 4, then we'll get a really cute little 22mp DSLR  with a 6-17.5/2.8 lens that would have pretty much the same resolution as the 5D3 ("Pretty much", because diffraction complicates things a bit).

Actually should be 6-17.5mm/F0.7 zoom that not only not cute and small anymore but impossible to be manufactured by a material named as "glass"

The f-stop is maintained if a lens is up/downscaled, because the f-stop is the ratio between the FL and the aperture diameter (which both are scaled by the same factor).

Yeah, it's the only way to make such lens small and cut on smaller crop sensor cameras.  But they don't perform at the same level and never will.

That’s why I keep using 600mm lens as an example if no "crop penalty".  Nobody should buy bulky and super expensive 600mm/F4.0 lens to use on FF cameras but should use 300mm/F4.0 on 2.0x crop mFT/FT cameras (such as E-5 or EM-5) or even better 30mm/F4.0 on a 20x crop camera to achieve the same resolution when you frame the subject into the same AOV. We know Olympus tried hard and failed badly in its E-x series DSLRs (how many if any still use at sideline of NFL or Olympic games?), no mention on a 20x crop camera, LOL.

Then you unable to demo in above 600mm case. I am sure 300mm/F4.0 lens on 18mp mFT/FT not only far less than native 600mm/F4.0 on 18mp FF (such as 1DX), it's even less than 12.8mp 5D in resolution test that your eyes can actually resolve. 600mm on 12.8mp 5D will receive 12+ P-MPix that almost has no loss but 300mm/F4.0 lens on a 18mp 2.0x crop will only have 5-6 P-MPix if DXOMark ever tested where you will see so-called crop penalty in every aspect clearly

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