Other Stereo Formats
Realist, or 5-perf format (named so because each image is 5 perforations wide on 35mm film), was the predominant stereo format of its day, and the easiest to find cameras, mounts and accessories for. However, in Europe, the wider 7-perf format (also known as European format) was the standard stereo format. Compared to Realist-format cameras, 7-perf cameras tend to be quite a bit more expensive on eBay. That said, the mounts are readily available, as are viewers that can either accommodate the wider frame, or that can be fairly easily modified to. A roll of 35mm film with 36 standard exposures can fit 20 7-perf stereo pairs. For information on 7-perf cameras, check out the deep dive in the following camera section.
Medium format can be a pain to work with, since there are basically no good mounts available (they exist but can rarely be found), and serviceable viewers are very infrequently on eBay, and usually of mediocre quality compared to the Realist format viewers, which were more mature products. You also only get 6 stereo pairs out of each role of 120 film. That said, the slides are huge, and offer unparalleled detail. Since slide film has such fine resolution to begin with, 35mm-based formats can be sufficient to create that sense of looking through a window into the world. But when there are faces or details that are distant or small within the frame, the additional resolution of the medium format images becomes very noticeable. Landscapes also look particularly expansive in this format. For information on medium format cameras, check out the deep dive in the following camera section.
Half Frame Format
Half frame (4-perf) is the format used by the 4-lensed Nimslo camera and its lesser plastic-lensed clones made by Nishika. It’s slightly smaller than the Realist format, and good slide mounts are available. While popular for making animated gifs due to taking 4 images instead of 2, these cameras are not as ideal for still stereo photography. For why, check out the deep dive in the following camera section.
Full Frame Format
Full frame (8-perf) is the the same size as a standard (non-stereo) 35mm frame. It is the largest standard stereo format shot on 35mm film, and not many cameras shoot it. For more information on shooting 8-perf, see the deep dive in the following camera section.
This is a very small format, stacking two rows of stereo images on top of each other on a single roll of film. As a result, Viewmaster images have significantly less detail and resolution compared to the other stereo formats. While the disc mounts and viewers are quite cool (and still can be found), I have not looked into them for this reason.