In checking the fourteen 4x5 Riteway film holders I've got, some of 'em have septum depths from the flats as much as .201". The 40 year old film that came with my SSG had black .004" thick 4x5" paper between each sheet. After sliding one of the black paper sheets in the septum of the holders with too much/little depth for me, the new depths came up to .196" to .197". Sheet film that's .008" thick slides on top of the paper sheets, but with a small bit of resistance atop the black paper that rides on the small raised ribs just below the septums lips that hold the film.
Seems to me like a decent way to salvage film holders whose septum depth is a bit deep (for me, that's greater than .199"; 2 thousandths deeper than the .197" spec. 12 of the holders now have depth to the effective septums of .195" to .198". That's a .003" spread that's well inside the .014" spread around .197" allowed by ANSI specs. 2 holders have one septum depth of .193" and .194"; these won't be used for critical sharpness. I think any depth less than .194" will begin to show image sharpness problems that increase with larger apertures and longer focal lengths.
And with the film held tighter in these shimmed-up septums, it'll stay in place better and not shift around 1/16th inch or more. There's enough clearance in most of the septums to allow gravity to pull the loaded film around as the SSG's orientation's changed.
Comments and suggestions welcomed.
Bart
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