With a fixed aperture of say 2.8 when you zoom out and reach the end it jumps to 3.2 by itself. It doesn’t happen every time and the first time it happened I thought I must have caught the aperture ring. Then the next time I thought oh I’ve done it again. So then I was extra careful and deliberate and it still happened. Not every time, best guess is one in five.Trying it at 3.2 it might jump to 3.6. Although it doesn’t happen every time its regular enough to make you paranoid and have to double check aperture on every shot, which is a pain. Yes I’ve double checked the connections and they’re clean and undamaged.