Question re Contax/Kiev mount

[chojna]

It has been bothering me for a long time ,so I thought I would ask

Why did Contax use an internal AND external mount ?
Why not one or the other ?
What was the benefit of the extra manufacturing cost ?
In the end weren't almost all the lens external mount anyway

Why did it take till the Kiev 5 to get rid of the internal mount?

Grateful for any enlightenment

 

[Sonnar Brian]

The 50mm normal lens uses the internal mount with its built in helical. Manufacturing cost of the 50mm lens is reduced. All of the other focal lengths must have their own helical, the one in the camera is calibrated for 50mm lenses. The lens' helical must "translate" focus movement into rotational movement for the helical built into the camera. The RF pickup for the camera is always off of the built-in helical, on Kiev, Contax, and Nikon. The results are more reproduceable than the system that Leica and Leica copies used, given that the film to flange distance is set properly. I have had to rework the RF cam of some Leica Thread Mount lenses, but never a Contax/Kiev/Nikon mount.

 

[VinceC]

It also makes the 50mm lenses quite small, much shorter than a film canister and not much bigger around -- they're just the optics and aperature mechanism with no focusing or rangefinder links.

Back in the 1930s - '50s (and later) the 50mm "normal" lens was the only lens most consumers owned, and nearly all cameras were optimized for it to some extent. High-end cameras such as Leica and Contax created interchangeable-mount systems to attract (a few) professionals and (a lot more) photography enthusiasts. So the Contax/Kiev's internal mount is designed for the lens that invariably came with the camera and, for most purchasers, the only lens that would ever be on it. And the highest unit-production lenses, the 50mm's, were easier to build. The Contax/Kiev mount is certainly a compromize, but its rapid-change bayonet feature was literally two-decades ahead of Leica in usability.

 

[furcafe]

In addition to the reasons given by Brian & Vince, I would say that Zeiss Ikon also believed that the focus wheel feature necessitated, or @ least favored, the use of the inner mount, as it doesn't really work w/larger, heavier lenses.