M40 (lens mount)

M40 is a standardized, manufacturer-independent lens connection for interchangeable lenses using a screw thread in the field of photo technology .

The "M" in the name stands for a metric diameter, the number for the diameter in millimeters. It is relatively rare and was in use mostly in the 1930s. The Praktiflex and Praktiflex II cameras from Praktica and Pentacon , which were manufactured up to the end of the 1940s , had this lens connection. It was introduced to avoid patent disputes with the M39 Leica thread.

Some CCD - line scan cameras still use the M40 mounting thread today.

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