Paul Rudolph first designed a symmetrical lens now known as a â€˜Protarâ€™ which was a highly corrected single combination lens which could be mounted with another lens in a single barrel to give even greater performance and a larger aperture.
His most important work was still to come, however, with the development of the Tessar lens in 1902. The Tessar comprised four elements in three groups, one positive crown glass element at the front, one negative flint glass element at the center and a negative plano-concave flint glass element cemented with a positive convex crown glass element at the rear.
The Tessar was hugely popular in mid-range cameras, and made photography a truly mobile activity for the first time. (A Tessar lens is still used on the Nokia Lumia 800 today.) With its small size and outstanding performance it delivers superb images.
There was one final step in the development of the ultimate ZEISS lens â€“ the technique of applying anti-reflective coating to lens surfaces. Applying multiple layers of coating was invented in 1935 and developed from this basis after World War Two, and known as â€œTâœ»â€ (T-star).
Does the Lumia 800 use a Tâœ»?