T-distance for plate holders ???

[Joe Smigiel]

Is/was there a t-distance standard for plate cameras? How different is the depth to the surface of a glass plate vs. film? And weren't old glass photo plates thinner? What, 2mm?

Anyone know? Is there a good reference with this sort of info? I have the ANSI standard for film rib-lock holders. Where can I find similar info for glass plate holders?

I'm particularly interested in specifications for quarter-plate, half-plate, whole-plate, and 11x14.

TIA

Joe

[Jim Noel]

I have never measured the T-distance, but believe it is the same. There were many plate holders made which had inserts to hold film also.
The thinnest glass I have been able to find to use is framers glass which has to be bought in large sheets and cut to size.

[dwross]

I shoot with a (rather embarrassing) number of different plate cameras of different formats. I've never noticed a focus problem that would indicate there is any difference from film.

In general, the smaller the format, the thinner the glass to fit the holders. Some take considerably thinner than 2mm. If you take your holders into a good glass shop, they'll be able to measure the right thickness and special order your glass (at least, that's what I do. Yay! Newport Glass!) I suppose it should go without saying that if you are planning on contact printing, you'll want to avoid UV blocking glass.

d

[Sevo]

Glass plates do not differ from film in that either are exposed on the emulsion side, and in general, the emulsion rides on rails or a frame, so that the depth of the glass plate or film itself does not come into play. If any, film holders are slightly more vulnerable to variations in film strength as they are lightly sprung or even unsprung - with glass plates in sprung holders, variations should not matter as long as the plate is thin enough to fit the holder at all.

[Joe Smigiel]

I found a relevant discussion of t-distances for whole-plate holders (http://www.apug.org/forums/forum192/38055-whole-plate-film-users-success.html) over on APUG.

Joe