Contarex Gas

[radi(c)al_cam]

Since I'm very happy with ZEISS Rolleiflex SL35 lenses, I definitely don't suggest to avoid Contarex lenses, but it's worth mentioning that after more than half a century they're not faultless; particularly the «shin oil» dilemma:
http://www.zeisscamera.com/services_overhaul-contarex.shtml