LTM (LeicaThread Mount) to M-mount Adapter Adventure III

This post is to help me keep track of what I’ve learned about adapting LTM lenses to modern digital Leica cameras.

While a LTM to M adapter may mechanically assemble the lens and the camera body it might not locate the lens on the camera exactly with the focus mark at the top. Example of mis-alignment with the Kipon adapter.

The mis-alignment isn’t an issue for focusing with the rangefinder.

LTM adapters that don’t incorporate 6-bit coding can be an issue because of the notch machined in the flange of the adapter. This notch exposes the optical sensor in the 6-bit coded M camera to variations in lighting. The variations in light causing the camera to “think” you’ve swapped the lens. The various lens modes on the M10 have different impacts when using this Voigtlander lens.

  • AUTO lens detect results in unpredictable interpretation by the camera. The results range from “no lens mounted” to the base default lens of 16-18-21 f/4.0 ASPH 11626. This is because the sensor is exposed to shadowing by you finger as you focus or any number of other things.
  • MANUAL lens setting can be set to whatever lens you are using, or an appropriate related lens. The issue remains that at times the camera will interpret a shadow crossing the sensor as mounting dis-mounting the lens. Generally when this happens, the camera switches to no lens mode. If you are rangefinder shooter, this might not be obvious to you. In LV view mode the camera puts up a warning screen “no lens mounted.”
  • OFF. This is obviously workable. The camera will function fine. You won’t get any EXIF data for the lens in this mode. Also, the camera will not perform any firmware correction for the particular lens mounted.

The absence of in-camera firmware corrections for lenses can be unimportant or a big deal. The lens that led me down this path, Voigtlander 21mm f/4.0 Color Skopar (LTM version), needs help from the in-camera firmware. If used without the Leica M lens selection set to 21 f/2.8 11134 you’ll get a magenta color fringe on the right side of the frame.

Magenta fringe along right edge of image. This happens with the Voigtlander 21mm f/4 Color Skopar LTM version when shooting without lens detection on M10-P.

Other Information about LTM adapters.

There is a good reference at Camera Quest that describes the various LTM adapters. There are definitely things to keep in mind when adapting the Leica thread mount to modern M bayonete with 6-bit coding.

Here is a discussion on l-camera-forum about adapting a 135mm Hector using LTM adapter.

< LTM Adventure II

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