The L-Mount Alliance

At Photokina 2018, Leica Camera AG announced together with Panasonic and SIGMA a strategic partnership. The “L-Mount Alliance” — a previously unparalleled form of collaboration that will particularly benefit the customers of all three partners.

The collaboration enables Panasonic and SIGMA to make use of the L-Mount standard — originally developed by Leica and introduced in April 2014 with the Leica T (Typ 701) camera — for their own developments and to offer both cameras and lenses utilizing this lens mount. As a joint effort of all three partners, this alliance will increase the importance of the L-Mount technology to world of photography even further.

On the same day, Panasonic announced its S1R and S1 full-frame L-mount cameras and three L-mount lenses, with seven more lenses to be launched by 2020, while Sigma announced that it will launch a full-frame camera in 2019, using the L-mount and the company's Foveon sensor, as well as a range of L-mount lenses and adapters for Sigma SA and Canon EF lenses.

The L-Mount has an inner diameter of 51.6mm and a flange depth of 20mm and currently there are two versions, an APS-C version (TL), which is not dust and splash proof and a full frame version (SL), which is dust and splash proof.
The two versions are mechanically and electronically compatible.
TL lenses mounted on the SL will instruct the camera to use a 10 megapixel crop-mode from the center of the sensor, corresponding to the APS-C coverage of the lens, while SL lenses mounted on TL camera, provide 1.5x crop field of view, like an APS-C camera.