The spurious hazy rectangle is suspiciously about the same size and shape as the film aperture, but is slightly displaced and skewed at an angle.
I think that you have a problem with the camera. Somehow unintended light is striking the film. I suspect a failure of the light baffle that normally covers the film aperture in the rear of the body when the reflex mirror is in the viewing position.
Normally it prevents stray light from reaching the film. It looks like light is somehow being reflected off of the rear surface of the out-of-position light baffle and onto the film, creating the hazy rectangle.
Yes, it resembles flare, but that doesn’t explain the offset rectangle with perfectly straight borders. Light reflected off of the rear of the light baffle might account for what you’ve shown.
Note the warning about not touching the light baffle on page 8 of the owner’s manual and this warning is repeated on page 16
It might fail on its own or have been tampered with at some point before you acquired the camera if it was bought used.
That this doesn’t happen on every frame indicates that the problem is intermittent. Eventually, it might occur more frequently if the problem gets worse.
Note that the hazy area is strongest at the top of the frame. I believe that the baffle pivots with the mirror. The bottom edge is likely the last part to cover the film aperture. Should the baffle “hang up”, the bottom might remain slightly open.
Any light between the not-quite-closed baffle and film would be somewhat stronger along the bottom than the top. Since the projected image is inverted on the film, the top of the scene corresponds to the bottom edge of the film. That’s where the hazy rectangle in the photo is strongest tending to support the idea that this might be a failure of the baffle to fully close.
Last edited by Ian C; 10-27-2012 at 12:00 PM. Click to view previous post history.