turret-mount

Definition: Two or more lenses set on a rotating plate so that one or either of the lenses can be locked into place on the optical axis for operation. * Now obsolete for stills photography but a standard feature in laboratory microscopes. Swing high, swing low Turret-mounted lenses were used e.g. on a viewfinder for the Leica but were never as popular on stills cameras as on cine-cameras e.g. Bolex where the lens designs were far more compact. Zoom lenses killed the turret-mount off for good, except in the laboratory microscopes where even now zoom optics are the exception, save with low-power stereo-microscopes.

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