C/Y lens to M-mount adapter that works with rangefinder ?

I'd like to adapt some of my Zeiss glass that I use on SLR Contax to an M-mount Zeiss Ikon. I realize now that the adapter I purchased does not accommodate focusing with a rangefinder. The lens would only focus by "guess". I don't want this, but I don't want to buy another set of lenses either.

Do you know of an adapter from C/Y lenses to M-mount that accommodates focusing with a rangefinder?

Thank you all,
-ejw-

Loose Gravel said:

I'd like to adaY of an adapter from C/Y lenses to M-mount that accommodates focusing with a rangefinder?

Thank you all,
-ejw-

Click to expand...

Oops ~ it doesn't exist.
The rear lug communication to the rangefinder base doesn't exist for these aftermarket adapters for retrofocussing C/Y SLR lenses to rangefinder M mount.

The easier zone focusing retrofocus C/Y Distagons are the 16/2.8, 18/4, 21/2.8 lenses - and the 25/2.8 at a pinch. The external viewfinders are less problematic for the standard focal lengths like 21mm.

An external watameter, external Leica or laser digital rangefinder works fine for uncoupled focus distance transfer although as a C/Y Zeiss photographer, you'd be better off using your Contax SLRs.

RF lenses need a cam to communicate the lens movement to the rangefinder. Each lens needs a specific cam that depends on the focal length. SLR lenses don't have that cam.

The exception would be a 50mm lens to which the RF is calibrated to. You would need to attach a straight cam on the moving part of the lens. Not practical.

Not really possible. If such an adapter did exist, it would be specific to a particular lens, and you might still be unhappy with the focusing accuracy. The tolerances on the true focal length of the lens (often a little different from the marked focal length) and the motion of the rangefinder cam are quite small.

If an adapter has the correct flange-focus distance, which is a lot easier to make correctly, then scale focusing (guess the distance) can work with wide angle lenses, especially if you stop down a little for depth of field. However, with SLR retrofocus wide angles adapted to a rangefinder, you lose one of the benefits of the RF, the ability to use very compact non-retrofocus wide angles.

There was a company ~15years ago that made an adapter to use SLR lenses on a Leica M as an Uncoupled Rangefinder. The adapter had a helical, distance scale, and RF cam. Measure the distance, set the lens.

It looks like Shoten sells something similar, but is coupled for 50mm lenses:


The other way to do it: buy a simple adapter and make your own RF Cam.

Minolta Rokkor-PG 50mm F1.4, wide-open. Focus from 0.65m to infinity.

At F4-

For other focal lengths- buy a bad-glass lens, take out the barrel, and use the focus mount. Disassembly required.

Just use your Contax/Yashica cameras for the Zeiss lenses.

I've seen adapters that have an uncoupled cam (coupled to the rangefinder but not the lens) that you get the distance info off of to transfer to the lens. That would be your best bet, but it won't be perfect of course. Wide angle lenses can be used more easily. Super wides can be used no problem since focus with them isn't very critical. I've never bought a 20 for my Leica since I can just adapt the lens I use on my Contax to it.