Choronzon,
with the mechanism outside the case, it is not possible to lock the "open time position". Anyway, I have found a trick to lock the mechanism with a piece of metal getting the aperture almost completely open. I have been able to install all the blades and to close the shutter without problems.
It works properly now! Thank you so much.
By the way, it seems that the pre-blades have to be installed on the top of the blades otherwise I will practically see them when I have the iris with the mechanism in front of me. According to the following photograph, which I had found on google, they are not visible:
What do you think about?
Best and many thanks. D.
Polaroid mp-4 shutter speed
Moderators: rjlittlefield, ChrisR, Chris S., Pau