Generic Lensboard Questsion

[Robert McClure]

My camera is designed (modified to accept) what I understand is a standard 4x4 lensboard. My question is this.

The wooden lensboard is 4"x4" by 1/8" in thickness. It nests or marries into a sliding rising front board with a square opening very slightly larger that 4x4 with a ledge or lip on it of 3/16."

In theory, this 3/16" ledge should trap light. As long as all associated surfaces are flat, and as long as the lensboard is held snugly against the surface to which it marries in the sliding front, should this be sufficient to trap all light?

Do I need a little felt, flat black paint, etc., or am I being a little obsessive? I remember my old Speed Graphic's lensboards were more ingeniously designed to be light/idiot-proof.

[ronald moravec]

As long as you know the front standard and and lens board are flat, no extra seal is needed. Knowing and thinking are two different things and you can`t ever assume the board or standard will not move slightly resulting in fogging all of a sudden and you will be chasing lightleaks after pic are ruined.

When I built boards for the Calumet 400`s, I applied 1/64 sq wood strips around the inside at the appropiate distance from the edge. Aircraft plywood was the base material.

[Tracy Storer]

Hi Robert,
there have been a lot of manufacturers that use 4"x4" wodden boards. The dimensions often vary slightly from exactly 4x4 to a 1/16th or so less. Board thickness and the dimensions of the rebate (reduced thickness "ledge" usually found on the back of the board) also varies some.
Zone VI boards fit quite a lot of cameras. It's pretty easy to knock out basic boards from a variety of materials on the table saw. (I've got a stack of Birch plywood 4x4s waiting for me to get motivated and drill them for some weird old lenses I want to test.) I guess I could go into the generic board market for anyone interested.
Hope this helps,
Tracy

[John_4185]

I sent someone here such a board. I know what you are talking about.

If the receiver has no expression to fit in the detent groove, and you are uncertain whether both are flat, just lay a piece of fuzzy cloth a bit larger than the detent in the groove (twine works). Press in the board, clamp, and you are good to go.

[Joseph O'Neil]

Any lens board I ahve made, I always painted the inside flat black. Dunno if is was essential, but I figured why not.

A belt sander with a fine grit sanding belt is invaluable for forming, shaping, smooting/roughing (inside) such generic lens boards. If you plan on making several of them, worth a look into

joe