Sony A6000 blurry in peripherals despite sharp center -- is this a mirrorless thing?

Question

I used to have a mirrorless Sony Alpha A6000 camera.

The problem I had with it was that, no matter how hard I tried to keep the center of my photos sharp, my photos always looked blurry in the peripherals.

To illustrate, here's an example -- zoom in & compare the left and right of the photo with the center:

I eventually sold the camera and got a Canon T5i, and I have not experienced this problem with it -- my photos turn out sharp everywhere with the T5i:

(Unfortunately, I didn't take photos of the same scenes with both, but trust me that I experienced this problem with practically every single one of my A6000 photos, and none of the T5i ones.)

Is this a known problem with the body or the stock lens? Or is it a problem with entry-level mirrorless cameras in general? Why does it seem hard to find any kind of information about this problem online?
The whole thing has been extremely surprising to me, because whenever I have searched online, the Sony A6000 has seemed to be universally regarded as a better camera than the Canon T5i, and I would never have expected its photos to turn out so comparatively awful. What's going on?

Why would you assume this is related to the camera and not the lens? — osullic, Jul 21 '16 at 09:47
@osullic: I guess for the same reason that the recommendations I find online don't say anything about the lens? Because I don't know better... — user541686, Jul 21 '16 at 10:18
You should probably read this question for the value of Snapsort for.... well, anything. — Philip Kendall, Jul 21 '16 at 10:20
@PhilipKendall: Thanks, good to know, but it's not like SnapSort is the only source saying A6000 is better without any mentions of any lens. Like I said, it seems a pretty universal recommendation -- do you disagree with it yourself? — user541686, Jul 21 '16 at 10:22
Images are formed by the lens. The body, essentially, is just a light-tight box, with a light-sensitive sensor sitting inside. Optical aberration is a "feature" of an optical lens. That's it in a nutshell. — osullic, Jul 21 '16 at 14:13
On the other hand, it's generally true that many mirrorless cameras use less-corrected lenses and rely on software. That's not inherently a mirrorless thing, but a tendency, both due to the fact that mirrorless systems are newer and because there's a pressure for small, light, cheap mirrorless lenses — mattdm, Jul 21 '16 at 19:38
@mattdm: I see. I'd be fine if the software actually corrected for this, but does (can) software do that? It seems impractical... — user541686, Jul 21 '16 at 19:56
strictly speaking, the question is a contradiction, because DSLR becomes mirrorless at the moment it takes a photo! — szulat, Jul 22 '16 at 18:56

score 5 · Answer 1 · edited Mar 10 '23 at 10:10

5

It is known problem with this lens.

Check out this review for measurements and samples for the stock lens.

Here is a more expensive one which does not exhibit this defect (made for Minolta A mount but adapted to NEX for testing): https://www.photozone.de/sony-alpha-aps-c-lens-tests/730-sony1650f28?start=1 . It seems that some design properties are causing this defect which are more often to happen with MILC.

I could also find an SLR objective that has this defect but I need to spend some time digging.

edited Mar 10 '23 at 10:10

Michael C

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answered Jul 21 '16 at 09:09

Euri Pinhollow

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Hm, but I don't see the problem in the samples, and I'm not sure which measurements you're referring to either. For example, if you look at this sample photo, sharpness seems pretty uniform across the image... nothing like the one I showed. – user541686 Jul 21 '16 at 09:14
+1 Oh, actually, I think I see what you're saying now! The MTF plots are a little hard to read for me, but when I look at the "Field map" under "Sharpness" in DXOMark, the difference is quote obvious: A6000 lens vs. T5i lens... however I'd love a more detailed answer if possible. Thanks so much for pointing me in this direction though! – user541686 Jul 21 '16 at 09:49
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@mehrdad: that one is done at F8 and does not obviously expose this problem (traces still visible in top left corner). Look at samples done at F3,5 or so. – Euri Pinhollow Jul 21 '16 at 10:05
Interesting... when I look at e.g. this one, it's awful vertically but rather uniform horizontally... which is sort of the opposite of what I see in my case. But otherwise it's the same effect, yeah. – user541686 Jul 21 '16 at 10:20
Regarding your edit, I see this field map which still seems to have this effect? (Compare with the A6000 lens and the T5i lens.) – user541686 Jul 21 '16 at 20:06
@mehrdad: "Interesting... when I look at e.g. this one, it's awful vertically but rather uniform horizontally.." the defect is radial - horizontal on the left and right and diagonal in the corners. – Euri Pinhollow Jul 22 '16 at 08:17
@mehrdad: field map does not say anything about type of blur which may be uniform or stretched. I edited the answer once again because the 10-18mm one seems to have this defect too. – Euri Pinhollow Jul 22 '16 at 08:30
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Both your links are Error 404, unfortunately. – gerrit Mar 01 '20 at 20:53
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Field curvature. It's a lens problem. – Zeiss Ikon Dec 28 '21 at 18:34

score 2 · Answer 2 · answered Dec 28 '21 at 19:20

If the "stock lens" is the SELP1650: It is known to sacrifice some edge performance for compactness when used at the extreme wide angle setting. Also, sometimes you read reports of there being badly decentered copies.

What is seen in the example image could be a) decentering (given the right side appears significantly worse), b) field curvature causing the plant in the foreground to be more out of focus than expected, c) subject movement (strong double lines in the same plant that look more like a movement artifact than bad foreground bokeh.)

Similar effects, for very different reasons, can appear on mirrorless cameras with some adapted lenses, especially wide angle lenses and zoom lenses. Here, the problems are usually either due to corner rays hitting the sensor (and thick glass filters in front of it, taking a longer path through glass than anticipated) at a very odd angle, or due to adapters that are inaccurate re: flange distance in conjunction with floating element lenses (which zooms and modern wide angles often are!).

Sony A6000 blurry in peripherals despite sharp center -- is this a mirrorless thing?

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