Check these photos I linked to out. I'm having an issue where within a roll of film I have a few but not all images with a big black spot (white on the print) They don't appear to be evenly spaced.

I have three theories on what it could be:

1.) My neckstrap hanging out and getting in front of my lens. I considered this more when I saw it on the first roll but have since developed more rolls from all various times. I think it would be crazy that I have such a habit like this, though not impossible!

2.) Something wrong with my camera. All were shot with a Leica M6, something could happen at a certain aperture, I don't know.

3.) My metal developing tank has a light leak.

All of the times this has occurred the images were shot on a Leica M6 and various films and developers have been used.

Any thoughts. I have some ideas on how to begin testing and eliminating variables but thought someone here might have just seen it already and know what my problem is!