Since there will be many new users here, who are not familiar with the history of the L-Mount system. I thought it would be a good idea to open a thread for this. If you search at Wikipedia, you will find this: So this L-mount existed already before the L-Mount alliance was founded. The L-Mount is owned by Leica and Leica only gives licences to Panasonic and Sigma to use the same mount for their cameras and lenses. This is different to the cooperation Panasonic has with Olympus with the MicroFourThird system. What i also learned in the meetings at Photokina was, that the L-Mount was modified slightly thanks to the input of Panasonic and Sigma. So the physical dimensions are the same as in the older Leica cameras with L-Mount, but the "communication" will be enhanced with the new L-Mount bodies in the future. I guess this was necessary to be easier compatible with the different lenses and bodies of Panasonic and Sigma. What I find also interesting for new users is that fact, that Leica already offers bodies with APS-C sensor size and the same L-Mount. This is like i.e. Nikon, who had over the last +40 years the "Nikon F-mount" for different sensor sizes (APS-C/DX and fullframe/FX and of course 35mm film). Although we are thinking at fullframe first, if we talk here about this new L-Mount alliance, there is always the option to use the same mount also for smaller sensors and there exist also already lenses for this smaller sensor size from Leica, which are of course also smaller in size than their fullframe lenses. These are the TL-lenses vs. the SL-lenses which are fullframe lenses. The L-mount is used by the Leica TL (discontinued), TL2, Leica CL (2017) and Leica SL systems plus the already announced cameras from Panasonic (Lumix S1R and S1) and Sigma (fullframe with Foveon sensor). So this new L-mount gives us many different alternatives also in the future.