Zeiss Sonnar

The Cooke triplet anastigmat, designed by Dennis Taylor and patented in 1893, was modified in 1916 by Charles C. Minor, who added a positive meniscus element to increase the maximum aperture to f/1.9, which was marketed as the Gundlach Ultrastigmat.

[9]: 112 Compared to Planar designs the Sonnar had more aberrations, but with fewer glass-to-air surfaces it had better contrast and less flare.

Though compared to the earlier Tessar design, its faster aperture and lower chromatic aberration was a significant improvement.

For example, the first Zeiss Biogon, a wide-angle lens for rangefinder cameras with a focal length of 35 mm, was derived by Bertele in 1934[10] from the improved 1932 Sonnar.

[9]: 128  However, the Sonnar design is incompatible with Single-lens reflex cameras (SLRs) due to the space taken up by an SLR's mirror.

[20]: 13–17 The Sonnar design has been extensively copied by other lens manufacturers, due to its excellent sharpness, low production cost and fast speed.