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.
Clinton and Tomoko-191.jpg
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...