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Archive 2021 · How much does lens sharpness matter on “lower” resolution cameras like A...

TheEmfinger
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p.1 #1 · p.1 #1 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

These days, how important is lens sharpness on cameras like the A7iii with “only” 24 MP over a large full frame sensor? Reading reviews of lenses, and they often use an A7R body for the review with much higher MP, and discuss how many lines it can resolve, but at some point it has to be outside the resolution of something like the A7iii or A7Siii. If I took a lens regard as very sharp and compared it to a lesser lens, would I notice the difference on one of these bodies? For a crop sensor or A7R camera, yea I see where you want as much sharpness as possible due to pixel density.

Apr 22, 2021 at 09:26 AM

AmbientMike
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p.1 #2 · p.1 #2 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

On film it was the other way around. Fujichrome 100 needed sharper lens vs Velvia for a given amount of sharpness (not sure how often 100 caught Velvia, though) So I'd think that 24mp needs more lens sharpness, to make up for lower resolution, but then I've read otherwise. So maybe digital is different?

But if you aren't getting more resolution on the higher res body using the same lens, I don't see the point of the higher res body. So you'd think you'd need less lens resolution on the higher res body, for the same sharpness.

Edited on Apr 22, 2021 at 10:20 AM · View previous versions

Apr 22, 2021 at 10:19 AM

QuietOC
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p.1 #3 · p.1 #3 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

There are optical filter differences between the models. The R models lack an optical low pass filter. The plain A7's have a filter that works in just one direction. The A9 and A7S models have normal two way filters.

A really sharp lens can alias too much on the R's and look better on an A9 or A7S. The R models will get more resolution from less sharp lenses. Or lens diffraction can be utilized. Downsampling images from the R models to a much lower resolution also works very well.

An A9 makes a lot of sense for professionals. Very little chance of anything ugly showing up. Less work and worry. The A7R's are slow and kinda ridiculous toys for amateurs. Of course professionals can enjoy toys too.

Apr 22, 2021 at 10:19 AM

AmbientMike
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p.1 #4 · p.1 #4 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

I was playing around with a 35-85/2.8 Series 1 a decade ago or so. Not so hot at 2.8 although very sharp at 5.6 or so. Not a perfect comparison since the 5D has a larger sensor, but it seemed maybe usable at 2.8 on 5D, better anyway, vs 40D, which is lower res.

Apr 22, 2021 at 10:28 AM

realVivek
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p.1 #5 · p.1 #5 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

AmbientMike wrote:
On film it was the other way around. Fujichrome 100 needed sharper lens vs Velvia for a given amount of sharpness (not sure how often 100 caught Velvia, though)

This is a case of contrast being mistaken for resolution.

Velvia 50 was a contrasty film. All sorts of tricks including over exposure was used to temper this.

Apr 22, 2021 at 10:40 AM

AmbientMike
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p.1 #6 · p.1 #6 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

realVivek wrote:
This is a case of contrast being mistaken for resolution.

Velvia 50 was a contrasty film. All sorts of tricks including over exposure was used to temper this.

No, its not. Velvia is a higher resolution film than Fujichrome 100.

Apr 22, 2021 at 11:33 AM

Petegh
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p.1 #7 · p.1 #7 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

Apr 23, 2021 at 04:42 AM

Slalom
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p.1 #8 · p.1 #8 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

Apr 23, 2021 at 08:29 AM

AmbientMike
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p.1 #9 · p.1 #9 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

AmbientMike wrote:
I was playing around with a 35-85/2.8 Series 1 a decade ago or so. Not so hot at 2.8 although very sharp at 5.6 or so. Not a perfect comparison since the 5D has a larger sensor, but it seemed maybe usable at 2.8 on 5D, better anyway, vs 40D, which is lower res.

Slalom wrote:
On the 40D you were looking at the centre of the image, This represented a portion of the 5D image, so maybe the edges were a little more focused than the centre or the 5D was able to get more from the whole image.

Nah, I was probably looking at the center on both. And I remember thinking it would be hard to get the resolution gains I was seeing using the same lenses on the 5D by buying better lenses for the 40D.

But if you aren't getting higher resolution on the higher resolution body or have to go buy a bunch of lenses to take advantage of the higher res, it's kind of pointless. And that's not what I saw on film. Maybe I bought into the 12 vs 100mp thread too much.

I think a lot of the stuff people say about resolution, contrast, diffraction etc is inaccurate and I tend to ignore it possibly roll my eyes and click elsewhere.

Apr 23, 2021 at 11:21 AM

Slalom
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p.1 #10 · p.1 #10 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

AmbientMike:

To clarify you only get the centre of the image on the 40D but you get the whole image from the lens on the 5D.

Apr 23, 2021 at 04:33 PM

DaveFP
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p.1 #11 · p.1 #11 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

If a given lens out-resolves a given sensor the difference will not be noticable.

I think you understand that so I am not sure what the question is.

In any case that fact would not prevent me from buying a higher resolving lens if I could afford it.

Bodies come and go.

Apr 23, 2021 at 05:00 PM

AmbientMike
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p.1 #12 · p.1 #12 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

Slalom wrote:
AmbientMike:

To clarify you only get the centre of the image on the 40D but you get the whole image from the lens on the 5D.

Right but that could potentially mean the lens is better on the 40D since any weak corners cut off. Certainly saw that on 17-35 Sigma

Apr 23, 2021 at 05:33 PM

fjablo
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p.1 #13 · p.1 #13 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

My understanding of system MTF is that - as it is a multiplication - every camera should benefit from a better lens. But the improvement is limited by the weakest element in the chain. In this case the camera.

E.g.
camera MTF 0.3 x good lens MTF 0.7 = 0.21
same camera + great lens: 0.3 x 0.9 = 0.27

higher res camera (MTF 0.7), same lenses:
0.7 x 0.7 = 0.49
0.7 x 0.9 = 0.63

So both cameras gain the same resolution from the better lens relatively, but in absolute terms the gains are much smaller on the low res body - up to the point of being hard to notice in real images. You would gain more by upgrading the body and keeping the lower res lens, than by upgrading the lens (in this example)

Apr 24, 2021 at 12:02 AM

Slalom
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p.1 #14 · p.1 #14 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

AmbientMike wrote:
Right but that could potentially mean the lens is better on the 40D since any weak corners cut off. Certainly saw that on 17-35 Sigma
So if another lens is better on the 5D, the edges must be at least decent to appear better than the 40D, assuming the centre is not wildly different.

Apr 24, 2021 at 04:19 AM

leonasj
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p.1 #15 · p.1 #15 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

does soft lens on 45mpix body will be sharper and more contrasty on then on 20mpix camera?

Apr 05, 2022 at 07:15 AM

tuomkok
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p.1 #16 · p.1 #16 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

leonasj wrote:
does soft lens on 45mpix body will be sharper and more contrasty on then on 20mpix camera?

That cannot be answered. More relevant would be to ask, is a soft lens sharper (less soft) on 45mpx camera than it is on 20mpx camera. We all know the answer

Also good to realize, basically all our cameras are high resolution in the sens that pictures are pictures are scaled down for viewing. Heck, even the ancient D700 was a high resolution camera compared to it's predecessors!

Apr 05, 2022 at 07:30 AM

MAubrey
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p.1 #17 · p.1 #17 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

Final resolution is a combination of both lens and sensor. A low resolving lens on a higher resolution camera will still resolve more detail than a high resolving lens on a low resolution camera.

Conversely, a high resolving lens and a low resolution sensor might actually resolve more detail than the low resolution lens on the high resolution sensor.

Citation: (page 22ff.)
https://lenspire.zeiss.com/photo/app/uploads/2018/04/CLN_MTF_Kurven_2_en.pdf

Edited on Apr 05, 2022 at 08:12 AM · View previous versions

Apr 05, 2022 at 07:34 AM

tuomkok
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p.1 #18 · p.1 #18 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

I fully agree with you MAubrey.

I would like to add that even in those cases where two lenses mach sensor resolution, there can be considerable differences in contrast, colors, transition between sharp and blurry areas etc. The things that are discussed under the topic of "rendering". In fact, most decent lenses are sharp enough, but they might lack that something extra that differentiates the best lenses from the rest.

Apr 05, 2022 at 08:10 AM

1bwana1
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p.1 #19 · p.1 #19 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

TheEmfinger wrote:
These days, how important is lens sharpness on cameras like the A7iii with “only” 24 MP over a large full frame sensor? Reading reviews of lenses, and they often use an A7R body for the review with much higher MP, and discuss how many lines it can resolve, but at some point it has to be outside the resolution of something like the A7iii or A7Siii. If I took a lens regard as very sharp and compared it to a lesser lens, would I notice the difference on one of these bodies? For a crop sensor or A7R camera, yea...Show more →

My experience is that glass matters no matter the resolution of the sensor.

Most modern lenses are sharp in the center stopped down a little. If edge to edge sharpness wide open is your goal, get the best resolving lens your budget allows with excellent corner performance. Also realize that other things like contrast, and aberration management do affect the perception of sharpness.

If story telling and mood is your goal for a lens, what is often regarded as flaws in performance can be used to help you shape the image. In such cases rendering may be much more important than outright sharpness.

Just like the care you give when you choose your camera body for a certain set of tasks, you should choose your lenses with as much care and intention.

In all cases, good glass matters. It shows.

Apr 05, 2022 at 08:27 AM

ruthenium
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p.1 #20 · p.1 #20 · How much does lens sharpness matter on “lower” resolution cameras like A7iii?

TheEmfinger wrote:
These days, how important is lens sharpness on cameras like the A7iii with “only” 24 MP over a large full frame sensor? Reading reviews of lenses, and they often use an A7R body for the review with much higher MP, and discuss how many lines it can resolve, but at some point it has to be outside the resolution of something like the A7iii or A7Siii. If I took a lens regard as very sharp and compared it to a lesser lens, would I notice the difference on one of these bodies? For a crop sensor or A7R camera, yea...Show more →

This is not an easy question. As was correctly noted above by fjablo, the system MTF = camera MTF x lens MTF.
A1 and A7IV can resolve more details than a 20 - 24 MP camera. To see how significant are the differences, please use dpreview image comparison tool. As an illustration, I attached a snapshot from dpreview. The differences in detail look significant to me. For example, to obtain a most detailed wildlife imaged, I would choose A1 camera system over A7III or OM-1.
In practical terms, for the very best image quality one needs BOTH the best glass and the best camera, i.e. the best camera system. Yet, as correctly noted above by DaveFP, "bodies come and go", thus buying the best glass is a good long-term strategy if you foresee yourself buying a new camera in the future.

Apr 05, 2022 at 09:40 AM

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