Need help diagnosing an odd problem
Didn't know where best to put this so I'm posting in this wedding section :)
I've been shooting wedding recently almost entirely on film and have had quite a lot of success, especially with black and white film and medium format color (using a Pentax 645).
However, I recently ran into an issue where one of cameras/lens with color film would strangely cause part of the image to darken and sometimes just downright underexposure the image.
Attached is a sample here of where the image was strangely darkened. And no, that's not my finger.
It usually happens when it's really sunny. The camera setup is as follows:
Nikon 35mm F1.4 Ai-S (or Ai).
Usually high shutter speed of 1/2000 or 1/1000.
I have a neutral density filter on those times (usually). The ND Filter is mounted by progressive step-up rings so the step-up rings look like a cone (52->55, 55->58, 58->etc etc until I get to 77, the size of the neutral density filter.
Portra 400 color film used.
Any suggestions? I'm very puzzled...