Bronica Classic Camera's Second Threaded Lens Mount Adapters

Markerink's Camera Mounts and Registers Page


Fig. 1

Fig. 2

Fig. 3

Fig. 7

Fig. 4

Fig. 5

Fig. 6

Bronica classic cameras of the S2/S2A and related camera series have a second threaded lens mount inside the standard bayonet lens mount (see fig.1). This threaded lens mount accepts lenses or adapters with a thread of 57x1 (57mm diameter and a pitch of 1 mm - see fig. 7). Using this second lens mounting setup, we can adapt a wide range of inexpensive lenses to physically mount onto the classic Bronica cameras.

These Bronica classic cameras also have a helical lens focusing mount as part of the body (not the lens). The standard bayonet mount lens do not have any helical focusing elements. Rather, this helical lens focusing mount is part of the camera body (or a separate element that locks on the body). In other words, the bayonet mount lenses are mainly glass. That is why they are less expensive to make and buy than similar leaf shutter lenses in medium format (see fig. 2).

The Bronica classic camera bodies also have a focal plane shutter. So Bronica lenses do not need to have an integral and expensive leaf shutter. Various Bronica classic cameras also have the option of working with leaf shutter lens too (e.g., a 105mm leaf shutter nikkor is available). But having both the shutter and helical focusing mount in the body is a major advantage to anyone wanting to experiment with lenses in medium format photography. You can use a lens without a built-in shutter or focusing mount, thanks to the Bronica focal plane shutter and helical focusing mount built onto the camera body. As our example here shows, you need little more than a threaded tube to mount your lens and use it!

This page shows an older Nikkor-Q 135mm f4 lens (fig.2) which has been mounted in an adapter machined from aluminum to match the lens threads. At the base, the ring is machined to match the 57mm diameter threaded mount and 1 mm pitch on the Bronica S2a camera (fig.3). The length of the adapter (fig.4) and position of the 57mm thread insert are set to bring the lens into infinity focus (fig.5). In use, the lens is focused wide open (f4). The preset aperture ring is turned just prior to exposure to stop down to the desired f-stop selected or preset on the lens. This technique is typical of preset lens use in general.

Unfortunately, you can't just use any lens in an adapter and have it work well with the Bronica threaded lens mount. The distance between the lens as mounted and the focal plane of the Bronica camera needs to permit focusing to infinity (fig.6).. For the Bronica bayonet mount, this lens registration distance is 101.70 mm. The threaded lens mount permits mounting a lens so it is somewhat recessed into the camera body. Even if you mount a lens so it just clears the mirror, you can't use most 35mm camera lenses on your Bronica camera. The distance to the film is just too great. Sorry about that! Moreover, whatever lenses you do use should be chosen to have the ability to cover the 6x6 cm format corner to corner, and without excessive light falloff.

But you can use an amazing variety of inexpensive and out of fashion lenses on adapters of various types and have a lot of fun doing so. Telephoto lenses are particularly easy to adapt and use. The threaded lens mount makes it possible to get a wide variety of lens options for your Bronica classic cameras.

In the meantime, you have an excuse to buy and try out a huge variety of lenses that can now be made to work with your Bronica classic camera. Whether you try an old polaroid camera lens to a high priced 8x10 format lens, you are likely to have fun and often be pleasantly surprised by the results! You will also learn a lot about how lenses work. Enjoy!

P.S. In a future article, we will also look at macrophotography options that this threaded lens mount adapter opens up for the Bronica classic camera owner.


Special Thanks to Mike Bond - DocBondo at AOL.COM for some of the ideas and inspiration to write this article!... From a reply in Photoshopper Medium Format Forum:

Hello Mike, I too use a Bronica S2A. Lenses from 50 to 200. I also make other lenses combos by cutting out old body caps and mounting antique brass barrel lenses. This is fun but the images tell the whole story. If you like very soft, you can do it. If you like tack sharp, that is also possible. Best of luck to you . Doc.





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