Zeiss Ultron 1,8/50 for Icarex - any information?

My latest akquisition is an Icarex 35S TM with a Carl Zeiss 1,8/50mm

Ultron lens. This lens is a strange beast. Icarex cameras were the

first Zeiss Ikon SLRs made after the Zeiss Ikon / Voigtländer merger

at the end of the 60s. Some of the Icarex TM (=M42) lenses are

Voigtländer designs, some are Zeiss designs, all had the Zeiss

designation on the front ring. Normally the lens names would indicate

the origin of the lens design, so a Distagon is a Zeiss design and an

Ultron or a Dynarex a Voigtländer design. With the Voigtländer VSL1

TM camera (which is nearly identical with an Icarex 35s) came a

1,8/50 Color-Ultron lens that is an exact Zeiss Planar copy. I have

one of those as well and it's definitely a different lens design

compared with the 1,8/50 Ultron. The Ultron has a concave front

element that no other Ultron labled Voigtländer lens seems to have;

this is a most unusual feature for a late 60's normal lens. So - is

this really a Voigtländer design? Can anybody give me more

information on this lens?

 

Peter

Havent read this whole site; your answer might be here though:

 

http://www.geocities.com/mjtolan/Rollei35Stuff.htm

The Vade Mecum, which isn't always right, says the 50/1.8 with concave outer surface of the front element is a Voigtlaender design.

I seem to recall that there was another Voigtlander design with a concave front element. Was it a 50mm for a Vito?