The Grimes folks mounted my 19" Artar into a Copal 3 shutter.

It is ever so much more elegant to be able to set the iris on f64, open the shutter and count off the seconds... then close the shutter.

More elegant by far, than it was to slip my lens sock shutter over the barrel mounted Artar, set the iris diaphragm to f64, slip off the sock shutter and count off the seconds, then slip my lens sock shutter back over the barrel mounted Artar.

Can't see any difference in the negatives, But...