Egy kis lencsetörténet, Tessar, Sonnar, Triotar, S-Xenar.

Carl Zeiss designed the Tessar 3,5/40 for the Rollei 35, it  was also made by Rollei under CZ license in Germany and Singapore. The cement for the third and fourth element was provided with UV depletion layer from 1968, it has simple lens coating. There was a Rollei 35 S-Xenar 3,5/40 (Schneider -Kreuznach) version, this is a Tessar type design with identical performance regarding the Tessar 3.5/40mm.

The Carl Zeiss design Sonnar 2,8/40 (above and below) was an improvement regarding the Tessar 3,5/40, the lens is moved as a whole for focusing and it has Rollei or CZ (T*) HFT multilayer coating; most Rollei 35 Sonnar lenses were made by Rollei under CZ license, the sample above is from the Rollei Fototechnik era, the button to retract the lens is now beside the lens according the Heinz Waaske original design, this way avoiding confusions with the shutter release button. 

The Triotar 3,5/40mm (below) was a decent coated cheaper lens for the simpler Rollei 35 models like Rollei B 35, Rollei C 35, Rollei 35 LED etc.

(Forrás: http://itarphotos.blogspot.hu/2011/02/rollei-35-lenses.html)