I have a 90mm 4x5 lens that is mounted on a copal 0 press shutter. I'm thinking of just moving this to a non-press shutter. Is it as simple as buying the new shutter and then just screwing the lens on? Also, the shutter I have now is f/6.8....will a new shutter that is f/5.6 actually give me that or is it based on the lens?