National Optical Company Anastigmat 2-inch 50.8mm f/2 (Collapsible)

National Optical Company Anastigmat 2-inch 50.8mm f/2 (Collapsible)

This rare English standard lens combines a collapsible barrel with a native, rangefinder-coupled Leica screw mount. Its nominal 2-inch focal length corresponds to approximately 50.8mm and its six-element, four-group construction gives it a distinct identity within the postwar M39 field.

Optical qualities

Rendering

The optical formula comprises six elements in four groups. The f/2 maximum aperture supports low-light use and selective focus, while results from surviving examples can vary with coating, haze and mechanical alignment.

Handling

The collapsible chrome barrel keeps the lens compact when stored. Published specifications indicate a closest focus of about 3.5 feet, or 1.07 metres, and an A36 accessory fitting. The conventional filter-diameter field is therefore left blank.

History

Development and Launch

A documented English-made example dates to approximately 1955. It was supplied as a genuine rangefinder-coupled M39 lens rather than as a modern conversion.

Production Evolution

Surviving documentation is too limited to establish a reliable sequence of revisions. The feet scale on the documented example is recorded as a production detail, not a separate model.

Special Editions/Variants

No separately documented optical edition is established. Engraving and scale differences should remain variants within this profile unless further mechanical evidence emerges.

Collector Notes

The National Optical Company maker engraving, original collapsible mechanism and working rangefinder cam are key identifiers. This profile remains separate from similarly specified Cooke and Taylor-Hobson lenses because the factory identity is different.