Recent and unusual German lens designs.

Some of the unusual lenses in the Carl Zeiss collection and those found in captured German equipment are shown diagrammatically, and constructional formulas and performance data are supplied. Many of the objectives are the Zeiss V (versuch—trial) lenses constructed to such formulas as appeared promising. Most of the lenses fail to fall in any of the usual classifications. Wide angle types include an f:2.8 distortionless objective and a 210° objective of the reversed telephoto type. The long focus objectives include the 300 cm f:25 telephoto lens used in the FK 3-m infra-red camera for photographing England from the French Coast. Wide aperture types include modifications of the triplet, Gauss and Sonnar types. Among these are objectives of f:1 and f:1.5 aperture used in the Bildwandler (infra-red image converter), and which possess focal lengths of from 9 to 40 cm. Experimental objectives utilizing one or more aspherical surfaces are described. References are made to the appropriate prior art.