Good link. I know Jack from DPR … he and Jim know everything …
Yes, the whole thing would be trivial if
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lenses had uniform sharpness across the whole frame (but they don’t)
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you used the same lens on different sensor sizes for the same purpose (but of course you do not, crop factor affects angle of view),
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there weren’t a thousand lenses out there with different lens designs, price, size, weight, etc that affects your lens choices.
Here, simply looking at the math is misleading; because, while the statement is of course technically true, practically it is not the relevant piece of information when choosing between lens mounts.
Incidentally, I find the statement
This is one of the reasons why Ansel Adams shot 4×5 and 8×10
funny. Of course it was the resolution of the film. You cannot magnify analog film beyond a point without a lot of artifacts. Which is why landscape photographers generally go for 40Mp resolution or more, and their full frame lenses are just fine for that purpose. Heck, some people shoot landscape with their APS-C Fujis.
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In terms of “good enough” lens resolution I can do a bit of a rough and ready calculation from this section on Subjective Quality Factor….
“Grainger found that he could correlate the subjective impression of sharpness with the MTF of the spatial frequencies in the print that correspond to the human visual response between 3 and 12 cycles per degree which turns out to be from 0.5 to 2 cycles per mm in the print when viewed at a distance of 34cm.
Grainger then developed a model, which basically states that the subjective sharpness of a print corresponds to the area under the MTF curve between the spatial frequencies of (0.5 x magnification) and (2 x magnification) when spatial frequency is plotted on a logarithmic scale. He verified this model by making prints using optical system with known MTFs and asking viewers to rate the images in terms of sharpness and he found very good agreement between his calculated SQF values and the subjective rating of image quality by viewers.
So to give a concrete example, if we make an 8x10 (or 8x12) print from a 35mm negative we have to magnify the negative by a factor of 8 (since the negative is approximately 1" x 1.5"). So as far as the SQF is concerned, the area under the MTF curve of the lens between 4 and 16 cycles/mm is then what really counts. The higher the MTF is in that region, the higher the print quality will appear to be and the higher the SQF will be.”
… and the lpmm figures on lens tip for various m4/3 lenses, where even relatively lowly lenses record above the necessary 32 cycles/mm (at reasonable apertures) implied by the SQF in the text above (adjusted for crop factor).
I think that makes sense, though as ever I’m prepared to be corrected.
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Another metric to consider is spatial frequency which correlates lens performance with sensor pixel density via an inverse square law. w(lens) vs sqrt(pixel density).
So, a 36MP Nikon D800 has a sqrt(pixel density) of 103 lp/mm and a 20MP Lumix DC-G9 MFT has a sqrt(pixel density) of 150 lp/mm.
So, on that basis, the answer is “yes” - it would appear that a lens for the DC-G9 needs better resolution in the image plane than a lens for the D800 - all else being equal.
Whether resolution is “resolving power” or not is still not quite clear to me.
** Moore’s Law.
https://users.monash.edu/~ckopp/telephoto-lenses.html
The “Bayer Effect” gets a mention here:
[url]https://users.monash.edu/~ckopp/bayer-patterns.html[/u]
It states that, for a lens there is quite a different need for “resolving power” between a Bayer-pattern sensor and a Foveon sensor. So the example D800’s sensor resolution of 103 lp/mm is really 51 lp/mm as far as a lens/camera combination is concerned - about the same as my 1.7 crop Sigma SD9’s 55 lp/mm.
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The Canon RF 28/2.8 has a cellphone-esque sequence of extremely aspherical lens elements molded out of plastic.
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I can’t wait for the gear snobs to say something like “Glass has more 3D pop than plastic” 
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More about sharpness than resolution but I had a chat with a wedding photography the other day who used to use full frame DSLR’s and manual focus but now uses a mirrorless Nikon with eye recognition auto focus which she says is nearly giving her a melt down, not finding normal auto focus up to snuff
So for that style of technically correct photography i would say the answer to your question is probably, yes
Not my style, though of course this doesn’t mean it’s wrong or I’m careless
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Note the topic is about optical properties, not AF. It is understood that correct focus is a prerequisite for sharp images, but different lenses provide different levels of sharpness even when the very same object is in focus.
Yeah, I imagine that Canon is testing the waters with this lens to see what happens. Personally I hope that these lenses become widespread for all MILC mounts, as they allow smaller (flatter), lighter, and less expensive lenses for the same optical quality, faster innovation cycles, and addressing more niche applications. I am especially excited given that lighter elements need less powerful AF motors (or can provide faster focusing with the same AF motor).
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I agree. I think people underestimate the know-how these companies have nowadays. Canon, Nikon, Zeiss etc are all in the lithography business which require extremely accurate optics. I would warrant a lot of material science, modeling etc eventually trickles down into consumer lenses.
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I wonder if these materials age optically as well as glass. Not that that’s a problem necessarily for the manufacturers. (edit: or to be honest, for many purchasers)
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yeah slightly off topic as conceded but all these areas are connected and interrelated
not focused enough on lens optics
I was considering widening the discussion to different media Pissaro seems a bit low res no optics though
The Avenue from the National Gallery under a Creative Commons license
less res on many others and other neoimpressionists if you do an image search
some in Scottish galleries
so maybe about perception as well as lens optics
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