Does anyone know why there is an extra non-threaded hole on the foot of my 100-500 lens collar? It would be nice if it was 1/4” 20 threaded so you could use 2 bolts to keep the plate from rotating but it isn’t. But is there some other use for it? I’ve always wondered..
Some tripod heads have a spring loaded pin that is used as a stop when seating the lens collar into the mount.
It doesn’t really need to be threaded. Some Arca-Swiss plates can use two screws. The screws can be tightened up to make a peg to go in the unthreaded hole to stop rotation.
