filmplane, gg distance issue

[Carioca]

Hi,
does anyone know the exact distance of the filmplane to the external frame of a 4x5 film holder? I do not have one handy at present, so I can't check myself. I've noticed different distances of my sinar and Linhof camera backs, regarding the gg and the frame. (3.7mm / 4.2mm)
Obviously sounds little, only (!) 0.5mm, but when shooting wide open as I do, it matters.
Is there some technician out there (with a precision depth meter), who knows what the 'official' distance is supposed to be?
(I'm using simple gg, no fresnels or brightscreens).
Thanks,

Sidney

[robc]

search the "Cameras & Camera Accessories" archives. This has been covered many times before here.

also read the link below.

http://www.largeformatphotography.info/holders.html

[Robert A. Zeichner]

The ANSI spec for 4x5 filmholder depth is .197" +/-.007". That said, the depth is from the outer frame of the holder to the surface of the septum. You will need to subtract the thickness of your film to get the distance to the film surface. Making these measurements is more difficult than you might think.