DIY 4x10 and 7x17 Film Holders dimensions

[ruckusman]

I'm going to be making both the camera backs and film holders for both of these formats, buuuuut.....

Checking these two pages

http://ssfilmholders.com/?page=critical_dimensions

and

http://www.filmholders.com/filmho1.html

I'm confused. The more I read the less I understand

1: There seem to be two competing 4x10 film holder dimensions

Which is the most popular? I know I read the rationale somewhere between the two different options, but it's a case of the more I read the less I remember some times.

Is it possible to cut 4x10 from 8x10 with one cut

2 7x17 film holder dimensions from the S&s film holders page don't make complete sense to me, for example the rob lock dimension is listed as 3/16" (4.8mm in metric) which is extremely large (wide) in my mind.

Also the two pages have different T dimensions?

I'm going to make the holders first then the backs, but would like make everything to the most current and "popular" specifications so any help appreciated

Thanks

Glenn

[robert fallis]

if your making the your own camera back and dark slides you may make them what size you like, to fit the film you intend to use, buy some cheap ortho film, to play around with.. the only critical dimension is that the focusing side of the ground glass lies in the same plane as the film emulsion.

and enjoy building your camera

bob

[Bruce Watson]

What I remember of 4x10 is that one film holder size was originally for Xray machines. And one was for LF photography (basically, half of an 8x10 holder). Some camera makers picked up on one, and some the other. I'd go with the LF photography size myself, which I believe will take film cut down from 8x10 film, one cut -- so if you cut it exactly in half, both resulting pieces will fit.

You could buy a single holder from Canham and use that as a template. Just sayin'...

As for the ULF sizes, from what I recall there were not really any standards for sizes above 8x10, but I never got into ULF so you shouldn't put a lot of faith in that. Surely someone with more ULF experience can give you some words of wisdom about 7x17.

[John Schneider]

http://www.largeformatphotography.in...t=4x10+holders

should tell you everything you need to know

[ruckusman]

OK I'm starting to get a clearer picture on all of this, I've had a look at the Canham film holder dimensions, and also at the pictures of the fotoman 4x10 holders, which are literally cut and glued 8x10 holders, so that makes sense as to why the 4x10 holders are slightly wider than 4x5 holders.

So I'll be going with the Canham dimensions on this. That way at least I have the option of buying available holders later if need be.

Cutting down 8x10 may suffice initially, is the available 4x10 film the same dimensions as 1/2 8x10?

So now I need to make the holders to accept available film.
For 7x17 I have a supply of 14"x17" commercial X-Ray film which I can cut in half, it's actual dimensions are 16.89" (429mm) x 13.89" (353mm).

How does this compare to pictorial emulsions (Bergger for example) available in 7"x17"? The X-Ray film will suit what I want to do initially, but I'd like to be able to accommodate faster available emulsions in the future.

[sanking]

So now I need to make the holders to accept available film.
For 7x17 I have a supply of 14"x17" commercial X-Ray film which I can cut in half, it's actual dimensions are 16.89" (429mm) x 13.89" (353mm).

How does this compare to pictorial emulsions (Bergger for example) available in 7"x17"? The X-Ray film will suit what I want to do initially, but I'd like to be able to accommodate faster available emulsions in the future.

The film slot on all currently produced 7X17" holders is a full 7X17". For the film to fit it must therefore be cut slightly smaller than 7X17". Typically the film will be actually measure about 16 15/16" X 6 15/16".

The S&S 7X17" holders that we sell today are virtually the same size as AWB and Chamonix holders in terms of width, thickness, rib-lock position, and T-dimension. The rib-lock of 7X17" holders is indeed 3/16" wide, designed to fall into a 1/4" groove in the camera back.

Please contact me directly if you have other questions.

Sandy King