Surly, take a look here and you'll see some excellent pictures of a large rotary shutter (in a 116 format box camera) and how to convert it to B-only operation. It should be pretty obvious how to make the B setting optional, and there's enough detail in those photos that you ought to be able to fabricate one with no other references.Originally Posted by Surly
If that doesn't do it for you, find any Ansco box camera and slip the front off by lifting the tabs on the two long sides off the short pins -- the whole shutter is right there, out in the open. If you get a 116, you might be able to simply take the whole shutter board and install it on your 4x5 box (saving a fair amount of labor). Alternately, e-mail me and I'll take some detailed pictures of the shutter in my Shur-Shot Jr.