I've taken some photos with my old Zenit-B camera. And I have some strange white spot on all of the photos in the upper right corner. Sometimes it is not too recognizable, but it is everywhere.
It looks like condensate, but I can't see anything like that on the lenses when I open camera. Also it is quite strange that this spot even appeared on absolutely dark photo.
Does anybody know what could it be and how could it be fixed?