Recessed lensboard problem

[Noah B]

Hello everyone, I recently got an older Cambo recessed lensboard and when I tighten the retaining ring it won't let me adjust the aperture scale. I tried two different lenses on it just to be safe, and there looks to be that the front of the lensboard isn't completely flat like a regular board, there is a small diameter around the hole that sits lower than the rest of the board which when tightened, won't allow for aperture adjustments. Is there a way around this or should I return the board and get a newer one? I've attached a picture and tried to describe it as best as I could, any advice is greatly appreciated.

97264

[Carsten Wolff]

Well, make a spacer (a cardboard ring will do).

[bobwysiwyg]

Or try your local ACE Hardware or auto parts place. They carry some easily cut gasket material in small rolls for a couple of $$'s. They come in either 1/32" or 1/16" thicknesses.