I have a 135mm Zeiss Jena lens with a Contax RF mount which I would like to use on my Fuji X-E1 camera. There are adapters for Contax, combo adapters and adapters for Nikon S. The Contax adapters are 200$ while the Nikon adapters are only 20$. They are mechanically compatible but apparently the flange depth of the Nikon is different from that of the Contax.

Does this matter for the 135mm since this is a rather long lens and the back focus should be less critical than with a 50mm.

2 Answers 2



According to Wikipedia the flange distance of these mounts is exactly the same, so you may not have an issue at at all. You should double-check the distances and probably fix Wikipedia if they are mistaken.

No. If you want to be able to focus at any distance, the flange distance has to be exact.

Otherwise, the lens may mount but you will lose the ability to focus at certain distances, sometimes even beyond a few centimeters.

The price of such things is usually based on product and demand, meaning either they produce so few that a higher price is needed to cover development costs or they perceive that people with Contax lenses are willing to pay more to preserve their investment.

  • 1
    They're flange-compatible. The difference is that the S-mount cameras couldn't use the longer Contax lenses because they would mount to the body helicoid rather than using the in-lens helicoid secondary mount. That means that the rangefinder coupling wouldn't work properly, and focusing much closer than infinity would be thrown way off. If you're focusing through the lens, there shouldn't be a problem.
    – user2719
    Jan 27, 2013 at 19:49

So I got one of the Nikon S-Mount adapters and the focus is just fine. The expensive adapters have an additional focus helicoid within the adapter which is not needed with this lens.

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