6x7 dimensions.....

The film gate size varies slightly from camera to camera.
I would use something like a film back for the original RB67 Pro - fewer interlocks.

 

The nominal size is 2.25x3.25" You may need to expose a sheet and actually measure it to get a more exact dimension.

 

Actually, 2.25" x 2.75" for 6x7

 

6x7 frame sizes vary by brand!

• the Mamiya RB67 image area is 56 x 69.5mm
• the Pentax67 image area is 55 x 70mm
• the Bronica GS-1 is 55.6 x 69mm

 

"Ideal Format" : 56 x 72mm

 

Wouldn't the actual film size be as the film size name ie 6cm x 7cm? Or am I missing something really obvious here???

Terry S

 

The best you can do is plan for 61mm. I'm not willing to pay for a copy of the ISO standard to obtain greater precision than that, but most secondary references, including this one

https://en.wikipedia.org/wiki/120_film​

call out "about 61mm." I suspect that, way back when, before metrification, earlier ASA standards started with 2.4 inches, so it's really 60.96mm.

 

The film is a standard size.
The edge printing and the need to have unexposed area around the outside of the image area is part of why the actual image sizes vary from camera to camera - particularly those cameras that work with interchangeable lenses.
It would be worthwhile to measure the "gate" of your enlarger's 6x7 negative carrier or your scanner's 6x7 negative holder - they are often slightly different than the size used in the cameras.

 

That accounts for different manufacturers' image width, i.e. across the film's roughly 61mm width, variations. Different image lengths (perpendicular to the roughly 61mm film width) are entirely arbitrary manufacturer decisions made for a variety of reasons.

For example, my Beseler 23CIII's "6x7" glassless carrier opening is only 53mm x 67mm. My LPL 4500II's "6x7" glassless negative carrier opening is 56mm x 69mm.

 

I'd wager it won't measure anywhere close to the commonly used misnomer "120mm."

 

Because, like 120, that's the numerical designation Kodak invented for it many, many moons ago. 135 refers to 35mm film in a cartridge/cassette. The number of standard 24x36mm frames it's capable of is appended as a hyphenated suffix. For example, 135-36, for 36 exposures.

 

A better question is why is 135 film referred to as 35mm film?
Well 135 film happens to be 35mm wide, so was 126 film and 828 film.
The still film version - 135 film - is quite similar to 35mm motion picture film, so it isn't totally surprising that people use the same designation for two different products.
Of course, the very first still cameras designed to use 35mm motion picture film didn't have any 135 film available to them - it didn't exist yet.

 

Re-reading the OP, it seems he is not interested in the 'frame dimensions' of the image area, but is more interested in the actual film dimension that is set aside for a shot to be taken.
A roll of Kodak 120 that I keep around is 61-1/2 mm (I do not specify decimal because I cannot accurately determine 61.4 vs. 61.5 vs 61.6mm, so I list a rounded (to nearest half millimeter) dimension.

 

There are some rules on camera gate, enlarger gate and slide mount gate, the latter two being one millimeter smaller.

But as the example of 6x7 cameras shows manufacturers varied on that.

 

Will you be cutting the 120 film to fit your film holder? ie. turning roll film into sheet film.

If so, it seems like a lot of hassle compared to removing the bellows etc. of a cheap folder and mating it to your pinhole cam.