Thanks Gerald, more recent schneider lenses seem to have the click stops which is kind of a mixed blessing. I am using it on a Meopta Magnifax 4, the lens board is around 76mm wide with a 39mm apature. I guess I can either get another board made up or something. The non-click is a bit of a pain in that it can be knocked, the solution again has been some blue tack to keep it in position.