![]() 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.
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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