how do #3, #4 etc shutters fit on lens

[Walter Gregg]

New at LF. Have bought a 5x7 with an old lens that has no shutter. I see adds for Copal #3 etc.....how do I know which shutter to buy....do I measure the fron t of the lens? I know about Packard but that will not fit on the back of my len s. What do you do when you don't have a shutter on the lens, other than removin g the cap to expose? Thank you. Walter

[mike rosenlof]

The shutter size is a bit more complex and depends on the size of the lens elements, maximum aperture, and how the lens mounted in the barrel with the iris. Check out www.skgrimes.com, Steve Grimes just mounted a lens into a shutter for me. If it's a well known lens, he can easily tell you which shutter it requires. He probably can if it's an obscure lens too.

This is not a job you want to do yourself. You must space the front and rear groups of elements properly.