Weird camera "flare" issue

[Ruben E]

Hi all!

I've noticed a very weird thing going on with my camera, a Sony A7III. All the pictures have a strange kind of semicircular "flare" appearing on one side of the image. It has happened with different lenses, so the problem doesn't look like it's there.

Weirdly enough, the issue changes depending on the focal length and light conditions, being barely noticeable when the picture is overexposed and it's thickness varying depending on the focal length, so it doesn't looks like it's a problem with the sensor, at least not to me, as it's also clean. I thought it could be some kind of light leak but the lens mount looks pretty solid.

Does somebody know what this issue could be? Frankly, it's driving me crazy. I'm attaching an example picture with a particularly noticeable "flare".

Thanks in advance.

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[XKAES]

Welcome to the FORUM.

Other people have had similar problems with flare, but this one seems different.  You might want to SEARCH the Forum's POSTS for FLARE to get some ideas.

Does this happen all the time?  Also, how long have you had the camera?  When did this start happening?  All of a sudden -- or is it gradually getting worse?

Edited January 23, 2023 by XKAES

[betterthanlife]

This is the mechanical shutter, Switch to full electric and it wont be there.

[XKAES]

I didn't think that the A7III had a mechanical shutter.

And anyway, how would a mechanical shutter create that effect?

[Pieter]

The A7iii has a mechanical shutter, as do all Sony E-mount cameras to date. But indeed: why would this issue be caused by the mechanical shutter? My best guess would be a leaking lens mount, but that is just a wild guess. Does it also happen if you wrap your left hand index finger and thumb around the lens mount?

[Ruben E]

Thanks for the replies, they have been very helpful and it has pointed me in the right direction. It is indeed a problem with the mechanical shutter, for what I've been able to investigate. I've just taken the camera to the technical service. At a first glance they told me that the damage could have been done because of using third party lenses, which doesn't make a lot of sense -honestly, I think they were just avoiding the responsibility. In any case, I hope that after it's been fixed it doesn't happen anymore. Thanks again! 

[FunWithCameras]

I have seen this kind of flare due to a problem with the mechanical shutter before, but that time the flare was straight and vertical - there was a hole in the leading edge of the second curtain, and it let more light through, causing the flare.

I can't explain the curve to this flare, but I can believe it's something to do with the shutter.

Fastest way to diagnose it is to try taking a shot with electronic shutter - if the problem vanishes, it's the mechanical shutter.