Tessar

Instead, the Tessar underwent a parallel evolution from Paul Rudolph's 1890 Anastigmat lens, which had four elements in two cemented groups.

[1][6]: 82–83  Hugh L. Aldis patented the Stigmatic lens line for Dallmeyer in 1895;[3] in one implementation, the front group from the Anastigmat design was modified by adding a narrow air gap, which acted as a positive element and improved zonal correction.

[9] Many models were equipped with Tessar lenses, which were marked as "Zeiss-Tessar", resulting in legal action from the Zeiss company in Western Germany.

[16] Other Tessar-type lenses include:[6]: 88 It is sometimes believed the Leitz Elmar 50 mm f/3.5, designed by Max Berek in 1920, was derived from the Tessar,[6]: 87  as they share the same general layout.

This lens, called the Elmax, gave good coverage of the 24×36 mm format and was used until improved optical glass allowed the third group to be simplified to a cemented pair when it was renamed Elmar.

It was not until Zeiss Ikon was developing the Contax camera to compete with the Leica that the Tessar was redesigned to cover a 24×36 mm negative.

Sony also uses Vario-Tessar lens branding for their consumer camcorders such as the HDR-CX405 extending the wide angle view with 1.9mm to 57mm zoom range.

Tessar lenses are frequently found in mid-range cameras, as they can provide a very good optical performance at a reasonable price, and are often quite compact.

They are also frequently used in photographic enlargers, as they provide more contrast than many competing lens designs due to the limited number of air-to-glass surfaces.

Some lenses, including Tessars, can be focused by moving lens elements relative to each other; this usually worsens optical performance to some extent, but is cheaper to implement.