Tri-lens turret

tri-lens turret


This is an almost legendary Leitz accessory, dating from the late 1950s. It allows the use of three screw-mount lenses on a Leica M body, all with rangefinder coupling and automatic frame selection: 35mm, 50mm and 90mm on the M2, and 50mm, 90mm and 135mm on the M3. This is possible because the flange-to-film register of the M is 1 mm shorter than on the screw bodies, while the throat is wider. With the appropriate adapter, you can use a screw-mount lens just as if it were a bayonet mount.

Three such adapters are built in to the tri-lens turret. Each lens screws into its appropriate screw-to-bayonet adapter (35/135mm, 50mm, 90mm), and thereafter the whole unit is controlled by a key on the back of the adapter, in the middle of the 'cloverleaf'. You can just about see the other end of the this key between the three lenses, on the front: shiny black on black wrinkle. The fit and finish of the whole thing is exemplary, as indeed it had to be in order to work at all.

Twist the key on the back, and there is a triple action. First, all three adapters rotate by the 15 degrees or so that is necessary to disengage the adapter from the body - though, of course, only one lens will actually be engaged at any one time. Twist it further, and the front of the 'clover leaf' moves forwards far enough to clear the adapters from the body. Twist a little more, and the whole 'clover leaf' rotates, bringing another lens in front of the body: there is a detent.

Now twist in the opposite direction, and the lenses are pulled back so that the adapter for the chosen focal length is inside the lens throat. Keep twisting and the adapters all rotate in perfect harmony, locking the chosen lens in place.

Of course it is ridiculously heavy, and not very well balanced, though the lollipop-style handle appears to have been designed only for use when changing lenses: trying to hold the whole assembly steady with your left hand, while operating all the other functions of the camera (focus, shutter speed, aperture, wind-on, release) with your right, is far from easy. Also, it assumes you already have three screw-mount lenses, and that you want to use them on your Leica M2 or M3.

Not entirely surprisingly, the market turned out to be tiny, which is why collectors drool over these things today. Even so, there are reputed to be two different versions, early and late. Roger found this one in a camera shop in Birmingham in the early 1980s and soon swapped it for something a good deal more useful; as far as he recalls, a new 90/2 Summicron. Seeing he only paid £100 for it, he wasn't too unhappy. To the best of our knowledge, the only other tri-lens turret for a full-frame 35mm still camera was the even rarer (and slighly earlier) Rectaflex Rotor.

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© 2010 Roger W. Hicks