I am building a camera using a very large front glass element for the lens (diameter is 70mm).
At first, I thought I should try to find a shutter that is 70mm in diameter as well, one that can function like older cameras (set the speed and aperture, push a lever, release shutter).
But now I wonder if I really have to use a shutter that is 70mm in diameter or larger, or if I can I use a smaller one? I am assuming that if I use a shutter of a smaller diameter than the lens, the properties of the lens will change (for example, it will become less fast), because of the smaller aperture ring behind it?
That said, are there shutters that are 70mm in diameter?