Is the space between frames on film standardised?

Question

Is the spacing between frames on different film formats standardised? I suspect it is not, but not sure.

I'm trying to figure out as much as possible about the dimensions of different film formats (135, 120, 4x5 et cetera). For example, 120 roll film is specified by the ISO standard 732:2000. This document (which you can buy from ISO, which I have done ... ) only supplies the outer dimensions for the film and the backing paper, it does not say anything about the internal relationships, like the spacing between frames.

I suspect these measurements were left up to the camera manufacturer. Like how different 6x7 cameras actually seem to have (small) differences in how big the frame is.

If so, is there a collection of data about different films and formats somewhere?

Answer 1

Here's a little secret¹: roll film has no aspect ratio at all until it is exposed. It is just one blank piece of film a specific width and any practical length, sometimes with perforations occupying the outer edges that leave a strip of a certain width in between the perforations.

What determines the dimensions of the photo is the size of the film plane each specific camera allows to be exposed each time the shutter is opened.

Movie cameras that used 135 format film, for instance, classically used a frame 24mm wide and 16mm tall (plus a 3mm gap between frames) as the film was going through the camera vertically oriented (the perforations were on the right and left of each frame).

135 format still image cameras typically run the same film size through in a horizontal direction and expose about 36mm of width along with the 24mm of height per frame (with the perforations above and below each frame) while leaving a 2mm spacing between the edges of each successive frame.² This is exactly twice the linear length of movie film that used 16mm + 3mm per frame. So movie film used exactly 4 sprocket holes per frame, 135 film uses exactly 8 sprocket holes per frame. The center of the sprocket holes are 4.75mm apart for all 135 format film, both for movies and stills.

Some film types, such as 135 format 35mm film, were more standardized across manufacturers lines. Other film types, such as medium and large format sheet film, were not. How much border between the exposed film and the edge of the standard sized negative could vary significantly from one camera maker to the next and sometimes even from one model to the next within a single maker's model lines.

Probably the most standardized format as far as roll film for still images goes was 135 film used in 35mm cameras. The camera usually allowed a 36x24mm area of film to be exposed, but not all of that area was usually included in the print. What was included in the print was fairly standard, though.

Back in the heyday of 35mm film cameras, most U.S. printing labs cropped each frame by around 5% to avoid printing rough edges. Most viewfinders on 35mm cameras were only about 95% coverage (so you didn't see the full field of view being exposed on the film, but rather the 95% that was actually going to be printed by most labs) or had a 100% viewfinder with indexing marks inscribed around the edges of the view screen that showed you where the 95% lines were. There were also technical issues with film that made the outer edges a little less precise than the middle of the frame in terms of optical performance. Japanese labs cropped the long edges only and printed the center 34.2mm x 24mm. Even today the standard 3R print size in Japan is 127mm x 89mm (5" x 3.5") which yields a ratio of ≈1.427:1. U.S. labs once did the same when producing 3 1/2" x 5" prints. When the U.S. moved to the larger 4" x 6" print, labs typically printed the center 34.2mm x 22.8mm of the 36mm x 24mm that was exposed.

The Wikipedia article for Film Format is a fairly comprehensive resource for various film formats that were offered and the size(s) of the exposed frame when using various films. As you can see on the first chart at that article, there were 4 common frame sizes that used 120/220 film (the only differences between 120 and 220 are whether or not it has opaque backing paper and the total length).

In addition to the ones listed at the article linked above, the Wikipedia article for 120 Film includes several additional format sizes.

_{¹ It's not really a secret, but there are a lot of folks who have shot film for a long time who don't realize this.
² https://en.wikipedia.org/wiki/135_film}

Answer 2

Any film without sprocket holes is unlikely to have any standard frame size or spacing between frames. As other people have said, 120 film standardizes the film (& backing paper) size, but not the frame size or the spacing between frames. There are many different frame sizes for 120, and spacing is inherently somewhat variable: the camera can't actually know quite how much film it's pulled forward because the film can slide over the rollers.

By contrast, any film with sprocket holes is very likely to have a fairly reliable spacing between the equivalent edges of neighbouring frames. The reason for this is that the camera is controlling the position of the film by a roller which engages with the sprockets on the film, and that roller is almost certainly going to advance by an integer number of sprocket-spacings. This is not quite always the case: there are cameras which don't seem to do this (which are a real pain to use), but almost all do.

What this means is that the spacing between the (say) left-hand edge of a frame and the left-hand edge of the subsequent frame will be pretty constant (assuming the camera is being used in landscape). Anyone who has cut 35mm film up into strips will have noticed this. But this isn't quite the same as saying that the spacing between frames is always the same, because the frames can be different sizes. Frames are nominally 24mm by 36mm, but they can vary in size significantly depending on the camera. Again, this is something that people who have made enlargements from 35mm will have discovered: you have to either adjust the mask, adjust the magnification (ie move the head) or both when changing to negs from a different camera.

For 35mm still film there are a bunch of standards of course, described here. 35mm film for still cameras is 'KS1870' which means it uses Kodak Standard perforations and the spacing is 0.1870 in. There are 8 perforations between subsequent full-frame edges (and I think 4 for half-frame). This means that subsequent full-frame edges are spaced by 1.496 in, which is 37.9984 mm: 38mm in other words. For a neg size of 24mm x 36mm this gives a spacing of 2mm between frames.

35mm film is well-standardised, of course, because it started as movie film and movie people really need to care about things like sprocket holes and frame spacing.

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Sheet film is less standardized. The two common extant varieties are 4in x 5in and 10in x 8in. There is a common film-holder standard (which has a name which I forget), but that standard is more concerned with making the film-holder fit the camera: the neg size between different models of film holder can vary somewhat. But there are other sheet-film sizes such as, for instance, whole plate and various fractions of a plate (half, quarter), where standards never really arose at all. Ilford have special yearly sales where they will cut sheet film to various odd sizes for people with these strange cameras (I really want a whole plate camera, although I can't afford the film for one realistically).

Answer 3

First, I don't know of any particular reference document or "collection of data about different films and formats." But, generally, the frame spacing varies from format to format, but is more standardised for a particular format.

On my 135 film for example, the spacing is always approx. 2–3 mm between frames, and in my current 6×7 films, is usually about 5–6 mm.

By the way, (if you haven't already discovered) the standard image size on 135mm film is 24×36 mm; on my 6×7 film the image size is 56×68 mm.

I have observed over years of using different 120/220 cameras, there have been some instances of very small (± 1–2 mm) differences in the image size of each image format between some 120/220 cameras. On another 6×7 camera I used several years ago, the image size for nominal 6×7 was actually 58×72 mm on the same 120 film.