Leica Mifflan distance

Most lenses with different bayonets cannot be switched. This is not a simple lens bayonet problem, but a lens flange distance problem. The so-called flange distance is the distance between the last piece of glass of the lens and the imaging film. Different brands of cameras have different flange distances. For example, the flange distance of Leica screw camera is 27.8MM, while that of Leica M-mount camera is 28.8 mm. That is to say, if an adapter ring with a thickness of 1MM is added to Leica lens, the flange distance is 27.8+ 1=28.8. The same is the Canon screw hole paraxial lens, although it is similar to Leica, but the flange distance is 28.8MM, plus the L-M swivel becomes 29.8MM, and the maximum aperture will move backwards when shooting. For example, the flange distance of Nikon paraxial lens is 34.85. If it is used in Leica M camera, it is necessary to shorten the flange distance of lens by 6.05MM, which is basically impossible because you need to redesign the lens barrel.