Mounting for a Sinar Shutter

In cases where a large diameter lens is being used in conjunctions with a Sinar Shutter, the lens casing can't protrude past the rear surface of the lens board. This particular brass barrel lens fits that bill. The lens required minor spacing to clear the rear of the board.

Complicating the matter was that the flange diameter was slightly larger than the lens board which would interfere with the standard's mounting latches. The flange and spacer could have been ground down to avoid conflict, but to preserve the integrity of the flange (an ultimately the lens); the step-up ring was machined to radius down to a diameter capable of clearing the levers.