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09-04-2021, 05:04 PM   #16
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The quality of APSC has been closing the gap for many years. Personally I have issues telling the difference, especially at web sizes...

09-04-2021, 05:44 PM   #17
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QuoteOriginally posted by mikesbike Quote
If quality of the lenses are even close, if the the two lenses on these two cameras will present the same FOV and therefore the same framing when shot from the same distance, the pixel density will be greater on the 36mp FF shot than with the 24mp APS-C shot.
That is right and if the lenses are only equal in their resolution (line pairs per mm) then there is the added bonus to the FF sensor of more overall resolution from using more of the image circle. But if the DA lens is built to a higher resolution (which may well be possible seeing it only has to cover the apsc sensor) then the apsc sensor can start to catch up with the FF. (That is why I feel you had your wording wrong in the earlier post)
09-04-2021, 05:54 PM   #18
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QuoteOriginally posted by biz-engineer Quote
So, let's say, the FF sensor is 1.5 x APSC size, but the FF lens resolve half of APSC at the edge (MTF50 apsc edge = 80%, and MTF50 @ FF edge = 40%)
I feel you are a bit over the top about resolution drop off in the corners. Take the K 50mm 1.4 - everyone knows it has a big drop off in the corners. courtesy of :
http://www.takinami.com/yoshihiko/photo/lens_test/pentax_normal.html

And remember the FF real estate is actually 2.25 times the area of apsc. For a given lens with no sharpness drop off that is 2.25 x the information from the image circle. I tend to round that off down to 2x to take in account corner softness.
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09-05-2021, 12:25 PM   #19
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The only test I've found for the DFA 24-70mm is the one by ephotozine. According to them, this lens performs way above average, both centrally and at edges. Results for both are very impressive. Perhaps there is a substandard copy in this case? The other good thing about this lens is its short end is down to 24mm, which also affords some wide angle if used on APS-C. The equivalency of 35-105mm f/2.8 would be quite attractive.

As for myself, I am very happy with the performance of my oldie-but-goodie Tokina ATX 28-70mm f/2.6-2.8 PRO II, which I bought new many years ago in a last-batch closeout deal. My copy has been delivering excellent performance, and consistently so edge-to-edge. Of course, even the best lenses will be somewhat better in the central area, but if edges are still very good, there will be a consistency throughout the image produced. When I don't need the wider aperture of the Tokina, I generally use the DFA 28-105mm on my K-1 II, which is very fine. I have been enjoying the HD FA 35mm f/2 with this camera lately. It makes for a much lighter, more compact easy-carrying ensemble with very high quality imaging, and its FL is excellent for general purpose use.

09-05-2021, 02:10 PM   #20
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QuoteOriginally posted by GUB Quote
I feel you are a bit over the top about resolution drop off in the corners.
That table is interesting but it's not reflecting my experience in terms of consistency between corners. Maybe that's worse with zooms at various focal lengths, but even with primes. I'd say only my macro lenses are pretty consistent between corners (and they also have relatively low corner falloff.) So while the best corners are usually pretty good for most lenses, that doesn't really help in real life when you have four corners to deal with, and at least a couple of them are pretty terrible.
09-05-2021, 02:51 PM   #21
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QuoteOriginally posted by tibbitts Quote
That table is interesting but it's not reflecting my experience in terms of consistency between corners. Maybe that's worse with zooms at various focal lengths, but even with primes. I'd say only my macro lenses are pretty consistent between corners (and they also have relatively low corner falloff.) So while the best corners are usually pretty good for most lenses, that doesn't really help in real life when you have four corners to deal with, and at least a couple of them are pretty terrible.
Looking at John Rileys tests in e photozine there is indeed zooms that are that bad at certain focal lengths. And his measurements are edge not corner. for instance here the FA24-90 @ 24.
I would be shocked it that was the standard for the latest glass.
But think about this in perspective of what this thread is about; Even if the entire FF area outside the apsc rectangle was at 50% resolution of the apsc rectangle the comparison would be ;

apsc image = amount of lens information within the apsc rectangle converted to digital via 24 mpixels

FF image = 1.6 times the information within the apsc rectangle converted to digital via 36 mpixels

( the 1.6 arises from the apsc rectangle plus a further 1.2 times that area at 50% resolution. So 1 + .6)
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09-05-2021, 03:04 PM   #22
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QuoteOriginally posted by GUB Quote
Looking at John Rileys tests in e photozine there is indeed zooms that are that bad at certain focal lengths. And his measurements are edge not corner. for instance here the FA24-90 @ 24.
I would be shocked it that was the standard for the latest glass.
But think about this in perspective of what this thread is about; Even if the entire FF area outside the apsc rectangle was at 50% resolution of the apsc rectangle the comparison would be ;

apsc image = amount of lens information within the apsc rectangle converted to digital via 24 mpixels

FF image = 1.6 times the information within the apsc rectangle converted to digital via 36 mpixels

( the 1.6 arises from the apsc rectangle plus a further 1.2 times that area at 50% resolution. So 1 + .6)
1.6 times the information doesn't mean it's good information. APSC just tests lenses harder, as long as the lens itself can stand the "magnification" of the APSC sensor and not be out-resolved in that part of the frame it can be sharper than on the FF camera. In reality you'd likely never notice the difference in a blind test because it'd be unlikely for a lens to be that good in the center and that bad in the corners, fov difference aside.

09-05-2021, 04:54 PM   #23
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QuoteOriginally posted by ZombieArmy Quote
1.6 times the information doesn't mean it's good information.
It is 1.6 rather than 2.2 to take into account it is not such "good" information.
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