Carl Zeiss Opton Sonnar 50mm f/1.5

Carl Zeiss Opton Sonnar 50mm f/1.5

The Carl Zeiss Opton Sonnar 50mm f/1.5 represents the first West German post-war generation of the fast Contax standard lens. Introduced in 1950, it uses a seven-element, three-group optical construction and factory-applied anti-reflection coating.

The lens fits the Contax inner bayonet. Unlike external-bayonet Contax lenses, it has no independent focusing helicoid. Focusing is performed by the camera's internal helical mechanism, which rotates the mounted lens and couples it to the rangefinder. The practical minimum focusing distance is approximately 0.9 metres, although this is partly determined by the camera body or adapter.

Optical qualities

Rendering

At f/1.5, the Sonnar combines a sharply defined central subject with gentler detail toward the outer field. Out-of-focus transitions are smooth, while highlights and brighter backgrounds can retain the characteristic structure of a fast, three-group Sonnar design.

Sharpness

Central sharpness is already useful at maximum aperture. The outer image is softer and more affected by residual aberrations. Stopping down to f/2.8 or f/4 produces a substantial increase in overall contrast and field consistency.

Vignetting and aberrations

Visible corner darkening is normal at f/1.5. Coma and reduced edge definition can appear around point light sources near the frame boundaries. These characteristics diminish as the aperture is closed.

Contrast and flare

Factory coating gives the Opton lens appreciably stronger contrast than an uncoated pre-war Sonnar. The small number of air-spaced groups also limits the number of reflective interfaces, although flare and veiling can still occur in demanding backlight.

History

Development and Launch

Production began in 1950 at the Carl Zeiss facility in Oberkochen. The Opton name identified this early West German production during a period when the use of the Carl Zeiss name was still contested between the eastern and western companies.

Production Evolution

Early lenses generally have an all-chrome appearance. A black filter-ring treatment appeared during subsequent production. Most examples stop down to f/16, although a smaller production variation with an f/22 setting is known.

By 1953, Carl Zeiss markings began replacing the Opton designation. The Opton-marked lenses remain a recognisable factory generation and are therefore maintained as a separate profile.

Special Editions and Variants

Chrome barrels, black filter-ring versions, differences in coating marks and the uncommon f/22 aperture scale are production variations within the Opton family. They share the same essential optical and mounting identity.

Collector Notes

Because the entire lens rotates during focusing, aperture operation can feel less direct than on a lens with its own helicoid. Check that the aperture ring moves freely throughout the focusing range. Internal haze, cleaning marks, coating damage and oil on the numerous diaphragm blades can materially affect performance and value.