The Stereo 12 uses the Graflok 45 / International standard, and thus it is compatible with any large format back (or cut film holder) that covers a least a 112mm wide frame. This includes 65mm (IMAX) film and 70mm film in our 65/70mm Panoramic Back, as well as our 65mm and 70mm cut film holders and Grafmatic septums, 120 film (in 6x12 backs), 4x5 sheet film (in sheet film holders or Grafmatic 45 backs), and specialty formats such as 4x5 instant formats, glass plates, tintypes, etc.

Mercury 70mm/65mm Panoramic back

We have made the Stereo 12 compatible with 70mm, 65mm, and 135 (35mm) film via specially re-engineered versions of the vintage Graflex RH50 back. We extensively machine the back and then re-build it with our custom-designed components. Our 65/70mm version exposes 70mm film or 65mm motion picture film in a full 6x12 format (actual image size: 56mm x 113mm). Not only can it be used with the Stereo 12, but also with the Stereo Pano Camera, and any other Graflok 45 mount camera, in which case it will produce a wide panoramic frame.

This back can also, with the addition of our "120 Adapter Kit for 65/70mm Panoramic Back," accept standard 120 film. This is an experimental feature and meant for occasional use or as a backup while traveling, etc. If you wish to shoot a large volume of 120 film, check out the dedicated 120 backs below.

Read about this back in the Mercury Stereo User Guide or check out our instructional video.

We have three modified sheet film holders available. These are modified from vintage combo metal/wood 4x5 sheet film holders. We cut Graflok grooves into them so that they can mount directly to the Stereo 12 without requiring the default rubber bands for 4x5 sheet film holders. This makes them much more convenient.

Mercury sheet film holder Graflok modified

Our second version also includes Graflok mounting, but takes 65mm motion picture film instead of 4x5 sheet film. This confers about a 90% cost reduction per shot, and is extremely useful for Mercury Stereo use as well as shoot flat panoramas on large format cameras (such as the Mercury Stereo Pano camera).

Mercury 65mm sheet film holder

To make loading our 65mm sheet film holder extremely easy, we also have a cutting guide that can be used in seconds to cut a 65mm strip from one of our bulk rolls and load the holder.

Mercury 65mm sheet film cutting guide

We also have a version of our cut film back and cutting guide that accept 70mm film instead of 65mm.

Cut film can be developed by tray, one at a time in our roll film reels, or via several custom Paterson and Jobo reels available in our store.

Read about cut film backs in the Mercury Stereo User Guide or check out our instructional video.

The legendary Grafmatic 45 is now, with a modest modification, compatible with the Stereo 12! This wonder of engineering allows you to load up to six frames (the same number as a 120 back) of any combination of different film types and formats (65mm, 70mm, and 4x5). The Grafmatic is one third of the cost, size, and weight of most 120 backs, and is far more capable. This is particularly useful when you want a slim configuration of your stereo camera.

Stereo Ready Grafmatic

Full instructions for the Grafmatic can be found in the Mercury Stereo User Guide, or check out our instructional video.

In 2025 Mercury Works released the Mercury 6x12 120 back, dramatically reducing the cost of our stereo cameras. This is a basic, no-frills back, but is specially engineered for stereo use. Unlike all other compatible 120 backs but the Linhof Techno Rollex, our back has a 117mm wide frame, large enough to shoot 50x50mm slides without modification!

Mercury 6x12 120 back

This is the lightest back available for the Stereo 12 and Stereo M (as well as for large format cameras). Its main shortcoming is that users must utilize its built-in window to line up 120 backing paper numbers while advancing the film, like the Da Yi back (below) and previous MF3D cameras before the Stereo 12. For rapid shooting, we recommend one of the 65/70mm back above, or the Linhof or Horseman backs below. But for standard use, the Mercury 120 back has proved to be quite robust, delivering outstanding images.

This back can be purchased here. Instructions can be found in the Mercury Stereo User Guide, and in this video.

While not needed by most photographers, Mercury Works has also occasionally produced a limited edition "Red" version of this back that uses even stronger materials, a stronger and smoother advance mechanism, and has a frame width of 120mm (sufficient for extra large 52x52mm slides).

Of the third party 120 backs that are readily available, the absolute best is the Linhof Techno Rollex 6x12 back, but it is very expensive, and thus we more commonly recommend the Horseman 6x12 or "6 EXP" back. It is beautifully made, loads and unloads like a dream, holds the film extremely flat, and can be operated via lever advance that is very rapid when needed, and never requires peering through a window and attempting to line up backing paper numbers.

This back produces a 56mm x 113mm usable image from the factory. It can, however, be machined by Mercury Works to modify it to a larger 56mm x 117mm image, enabling wider mounted slides (up to 50mm).

Horseman 6x12 "6 EXP" 120 back

The most economical metal 120 back, currently in production, is the Chinese Da Yi 6x12 back. This is a solidly made back and a decent value. It is clunky and can require a bit of adjustment for optimal functioning, and is relatively difficult to load and unload. After the release of the Mercury 6x12 120 back, we no longer recommend this one, as the Mercury one has a similar design, but is half the price, has a larger frame width, is easier to load and unload, is significantly lighter, and has other features like a film memo holder. Mercury Works has developed an upgrade to this back, however, that enlarges the film width to 120mm, makes it a bit easier to open and seal (though still not as easy as the Mercury back), and adds a film memo holder. If you are an experienced machinist you can perform some of these modifications yourself using our instructions, or Mercury Works can perform this modification.

Da Yi 6x12 120 back

Mercury 135 Panoramic back

We have also made, as a special one-time-only batch, a 135 version of our panoramic back. It can accept regular 135 cassettes or up to 15ft of bulk 135 film. It can feed from and takeup into 70mm cassettes for extra protection. On the Stereo 12 it produces a roughly 2.35:1 aspect ratio (Cinemascope format!). On a large format camera it produces a really long panoramic image of roughly 4.6:1! This back was produced as a one-time batch and is sold out.

Mercury Instax Wide Motorized Back

This back, originally for the Mercury Universal system, is now updated and compatible with the Mercury Stereo system, enabling shooting instant stereo photos! We call this system Instax 3D. For more info, see the Instax 3D section on the cameras page.