Beseler VC Filters #8045

I just picked up my first set of Beseler variable contrast filters (#8045) from the auction site which is mostly complete but they all seem to have a convex/concave (varies) shape to them, they are not flat as I expected. It appears they may have been heat damaged? Normal shape? If not normal, I don't think the distortion will hurt as they are located above the lens as long as the distortion doesn't prevent them from sliding into the enlarger. True?

Anyone?

Fred

Sounds like heat or age damage. They are supposed to be flat. You can check the effect with a focus magnifier under the enlarger but if given a choice I'd try to find a set in better shape.

Well, it looks like I was bitten by the eBay snake and will write this one off.

Fred