I hope someone who owns a Mamiya 645 150mm leaf shutter lens can give me some advice! I bought one a while ago but haven't been able to use it. Basically, I cocked the shutter but the shutter remains firmly closed! (It should have opened when it was cocked by turning the cocking-ring.) :confused: I've never actually had the shutter open and I guess it's jammed. It was a while before I tried to use the lens because I was hoping to find some instructions for it. (I've used an RB leaf-shutter lens in the past but it was a long while ago...) I did find an instruction booklet for the Mamiya 70mm leaf-shutter, which is similar but not quite the same. As far as I can see, I'm doing everything correctly but getting nowhere. Without the instructions for the specific lens it's hard to know if I am doing something wrong! Any suggestions? All advice gratefuuly received! Thanks, in hope and anticipation, Ann.