Mamiya RZ67 Polaroid Back Light Leak
No worries, I realized I had done it and partly because I was in a rush I attached the back when the camera was upside down and that's why I didn't notice.
Obviously if it continues there's some other issue, take ONE shot in super bright light, shine a flashlight all around it and leave it under a bright lamp, all with the dark slide OUT, then take a picture with normal exposure, THEN put the dark slide in, THEN pull the tab and pull the single film out, wait the minute and a half to let it develop, then pull them apart and see what it looks like, if its fine then it was user error, if not its some other issue (could even be the lens shutter or some other issue unrelated to the back.
Good luck and Happy New Year!
Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk