Dallmeyer Dallon 4-inch 101.6mm f/5.6

Dallmeyer Dallon 4-inch 101.6mm f/5.6

The Dallon 4-inch f/5.6 is an early British telephoto made in an original Leica screw mount. Its compact telephoto layout and dedicated focusing barrel offered a roughly 102mm field of view for early interchangeable-lens Leica cameras, without rangefinder coupling.

Optical Qualities

The Dallon belongs to Dallmeyer's Tele-Anastigmat family and uses a shortened telephoto arrangement. The 4-inch focal length equals approximately 101.6mm and provides a useful short-telephoto perspective on 35mm film. A dependable elements-and-groups count for this exact barrel has not been established and is left open.

History

A documented black-and-chrome example dates from 1931 and was supplied for an early Leica I Model C. Later auction records confirm the 4-inch Dallon in an original Leica M39 mount. Its uncoupled construction reflects the early period in which interchangeable Leica lenses were commonly scale focused.

Handling

The lens focuses with its own helicoid, but it does not drive the camera rangefinder. Distance must therefore be estimated or measured externally. A separate finder with an approximately 100mm field of view is recommended for framing. Reliable minimum-focus, filter and diaphragm data are left open.

Compatibility

The original lens uses the Leica thread mount, also known as LTM or M39, at the Leica register. It mounts directly on compatible screw-mount cameras and can be adapted to Leica M. It is not rangefinder coupled.

Sources

• Leitz Photographica Auction, Dallmeyer Dallon 5.6/4-inch
• Leitz Photographica Auction, early 1931 Dallon 5.6/4-inch
• Science Museum Group, Dallon Tele-Anastigmat history