Hello!
Getting straight to the point: the middle auto focus point in my D3500 (both in single point and dinamic-are af, in continuous or single AF mode) doesn't seem to be working propperly. it hunts endlessly and it usually ends at closest focusing distance, and it gives up from there. It can still focus fine on really bright object. Yesterday, most other points were also having the same problem, but now only the middle one still has it.
I have tried to carefully «shake off» any dusk in the AF sensor (I now it isn't a great a idea, but I don't have any blower), but it didn't help anything.
Also, there is a weird circle when looking through the viewfinder around the middle AF point (photo below). It's hard to see on the photo, but it's clearly visible when looking through the viewfinder. I've noticed it before, but didn't think much of it. Maybe it's related?
Anyways, thanks in advance to anyone who can offer any help or advice.