Designed to the amateur market the Contaflex was an excellent option for those keen to enjoy the Reflex feature without paying about the double by a Contax reflex our an Exacta Varex. The system had several lenses and accessories. The lens rear elements are part of camera body. To go from 35 to 115 mm only the front elements are changed. But this doesn't save weigh or size compared to Voigtlander or Kodak reflexes, also from the fifties, in which the whole lens comes out. It uses a leaf shutter that it is perfect for flash synchronization up to 1/500. It is a pity that you can't hear how silent it is due to the not so discrete "clap" of the mirror. There are backs you can buy and change while loaded with film,but nowadays they are so expensive as another body.

The Super B, launched in 1962 was already a stepchange introducing the first 35mm camera with automatic exposure. But it used a Selinium meter that was loosing share to the new CdS. The Contaflex Super BC in 1965 went even further and had a coupled CdS meter TTL! Together with the Ultramatic CS from Voigtlander it was again the first 35 with TTL metering.
It is a nice camera to use but it has its idiosyncrasies: to focus it is the same ring with two nobs (see picture) whatever lens you are using. This is not very comfortable mainly with the heavy 115 mm hanging on it.
Comparing rangefinders to modern reflexes the first ones are are much easier to focus under low light conditions (when coupled with telemeter). On top of that a rangefinders does not blind you at the very moment you fire (for reflexes it is either you or the film). So the aparent "what you see is what you get" of this system is ironically not true exactly at the moment you are actually taking the picture. This makes a big difference in low speeds and when using flashes. But this is for modern reflexes, for the first ones like Contaflex, Bessamatic end Retina (the ones I have) this was even worse because the mirror doesn't go back to position. The moment you press the shutter you say goodbye to your subject. You will see it again only after winding another frame. The only reason for the success of this system for me is due to no paralax error whatever lens or distance you are shooting and that you can focus always in the same viewer, the same way. Nowadays at the end of film era, with modern paralax correction and auto-focus, rangefinders are coming back, just to say good bye for ever. You can have look also on the   Contaflex IV  an earlier model,   Retina Reflex III  from Kodak and the   Bessamatic  from Voigtlander.