A round shadow or ghost appears in the centre of the image

[eugeniofarri]

Hi Sony Community, 

I'm trying to understand something that started happening recently using my Sony A7IV + 100-400GM lens which I have used for the last 2  1/2 years. After a cold day in the snow recently, I have noticed a shadow in the centre of my photos and I don't see any solution online as to why this is happening. I can live with the usual vignette but this circle in the middle is bothering me a lot. 

I have attached the same photo (one over dehaze to accentuate the circle so it's very evident, and the others is for you to see that even with normal editing I can still see the circle (especially in the small thumbnail down in Lightroom Classic) I have tried removing the neutral filter from the lens, shooting settings, but it seems to be always there (at 400mm is more evident) 

Any one with the same issue?? 

 

[danardeng]

Does it change changing the length of the zoom, the distance of the subject (minimum distance focus to infinity), and diaphragm aperture?

[danardeng]

Can you find the moment in your photos sequence when it appears? Can you recognise what’s happening in that moment?

[eugeniofarri]

Definitely appears at 400mm focused on infinity. Is not so evident when at 400mm but focused on a close subject.

At different zoom lenghts (300; 200; 135 & 100mm) the shadow becomes bigger and closer to the usual vignette.

At f5.6 dissapears, but at f13 the shadow's edges become harsh (as if you were reducing the feather in a brush using LRC) The shadow appears from f8 onwards. 

Not sure if relevant, but since the problem started yesterday, just in case I have updated the lens firmware today, however the problem still persist.

[danardeng]

Have you checked when it’s appeared in your image archive?

[eugeniofarri]

By image archive you mean if previous photos were affected too? They are fine, the affected photos started to appear after a cold day out taking photos in the snow. 

[danardeng]

Yes, you said. But have you found the pic before and the pic after the event, or there is not a clear transition before/after?

[eugeniofarri]

Right, no there is no clear transition, as I finish taking photos last Sunday, edited the photos of that day and it was all fine. Put the camera away, and when I took it again to shoot some landscapes with the moon last Friday afternoon, is when I've noticed the issue. 

[daveyh64]

As you said in your first post you took the camera out to shoot in very cold circumstances could this circular

'bloom' be caused by taking the camera  out of a warm environment into a very cold one.

It may be condensation on the back of the lens, have you taken the lens off the camera to have a look.

When travelling with the camera do you keep silicon gel packs beside the camera to prevent moisture build up.

[eugeniofarri]

Will check again, from my assessment, there was no condensation signs. I took the camera from a warm place but sent probably an hour walking on a cold enviroment with the camera in my backpack, then took it out and shot for two hours or so, cameback home and the photos were fine (from this session) 

The photos after that are the ones clearly having this shade in the middle. I might have to take it to Sony for a more technical review, I guess.