[stoppingdown]

I've started doing a few tests yesterday with my new lens. For the first time I have a disappointed feeling about a new lens, even though in most cases they are related to defects that are well known from the review (and don't get me wrong, the lens is excellent for the price under many respects). It is something related to vignetting wide open, but not the regular one that I expected — to cut the story short, it's a strong horizontal vignetting that only appears at the lower border. Indeed a possibility is that it's related the fact that the mechanical vignetting seems not centered. I'm going to post a few samples below.

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Well, I'd like to post the photos, but it seems that attachments are not working...

[MLonlooker]

I'd return it while it's still in the 14 day window ..........

[Timothy324]

It looks like you are having problems with vignetting not being as expected. Try checking your lens usage or consider other factors!

[stoppingdown]

Of course. Before doing that, I'd be curious to understand what the problem actually is. Because sharpness is ok, so it's not a matter of decentered elements. What could be that decenters vignetting but not sharpness? Also, while the problem is perfectly reproducible, in some bursts I see it happens with different intensity. But the only thing that changes in the burst is the shutter time. At first I even thought that was due to the shutter my a6300 (the oldest camera body), but the problem happens also with the newer cameras.

[toni-a]

Maybe there's a problem with the aperture, this should be easy to spot looking at the boken that would take the shape of the aperture and how it would change when you close the aprture

[stoppingdown]

The plot thickens. I got a new copy from Amazon (the former copy was bought from another reputable shop), and it shows the same behaviour. Chances that both lenses are from an hypothetical defective batch are very low.

Furthermore, new questions:

1. Why don't I see the problem in the EVF? Shots are at full aperture, so the diaphragm stays in the same position before and during the shot.
2. Running a test keeping ƒ/1.7 but changing the shutter time, the problem slightly decreases shortening the shutter time, until it goes out. So... maybe is it related to the shutter rather than the diaphragm? But how could that happen? Both the camera bodies I'm using have no problems at all with other lenses.

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Using the silent shutter of the a6600 (electronic only) the problem doesn't happen... So maybe is it really a strange interaction with the shutter?

[stoppingdown]

BTW, not related with the issue, but since I'm testing this lens I'm adding this here... Both copies decentered at full aperture, one within the reasonable margin, the other well beyond.

[stoppingdown]

I've posted a couple of test shots here:

https://drive.google.com/file/d/1CU1AH4w...AMmT0/view

Both same speed (1/4000s) and aperture (ƒ/1.8), ISO 100, a6700, mechanical shutter and electronic shutter.
After these tests, things are even stranger: the dark banding at the lower side is not present with the electronic shutter... but it's at the upper border. In previous tests I didn't notice it.

[MLonlooker]

I've posted a couple of test shots here:

https://drive.google.com/file/d/1CU1AH4w...AMmT0/view

Both same speed (1/4000s) and aperture (ƒ/1.8), ISO 100, a6700, mechanical shutter and electronic shutter.
After these tests, things are even stranger: the dark banding at the lower side is not present with the electronic shutter... but it's at the upper border. In previous tests I didn't notice it.

I finally found these images ..... have you tried taking these images at a lower shutter speed to see if this changes the dark areas? 1/4000s may be the source of the issue ... just a thought!

[stoppingdown]

Fast shutter speed is the main suspect now indeed: slowing the shutter the intensity of the problem seems to diminish, and longer than 1/1000s (more or less) disappears. But the shutter is managed by the camera body, and nothing similar happens with the other fast lenses I have. So, maybe a camera malfunction induced by the lens firmware? Very strange.

I thought also about the correction profile in Capture One. This could be an explanation on why so far nobody reported the problem: the first version of the lens was Fuji, so different firmware etc., and most reviewers basically did a thorough review of that version.

OTOH, Klaus in his review wrote:

This (vignetting) is a rather interesting difference compared to the X-mount version which produced a far lower vignetting in RAW mode. This may relate to the different tone curve in E-mount or a different sensor characteristic.

It would be interesting if Klaus could comment more about what he saw.

But I tried to disable the correction profile in C1 and also opened the photos with RawTherapee. Problem still there.

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BTW: there are recurring discussions about whether Sony already bakes some corrections in the RAW file (which in theory shouldn't, but...), anyway there are people saying they proved it and others saying the opposite — and I never was able to understand who's right.

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Also, there are two new tests to see:

https://drive.google.com/file/d/1x7R9mdI...XQB3d/view

Note how the trees are darker at the left, while the sky is darker at the right.


https://drive.google.com/file/d/1CU1AH4w...AMmT0/view

These are shots of the blue sky, defocused, converted in b/w and contrast exaggerated, to make the problem more visible.