What is M12 Mount
M12 means that the diameter of the lens thread is 12mm, and it’s also known as the S-Mount lens because is S(Small) compared to the C/CS mount lenses.
What is M12 Lens
M12 lens is a series of lenses to be installed in the M12 mount lens base, usually used for applications where compact size is required. The M12 lens was initially widely used on CCTV cameras for surveillance. Like other lenses, the M12 lenses come with different focal lengths and formats to fit the requirements of different camera applications. You can learn more about it on this page.
Why M12 lenses on Raspberry Pi and other embedded systems
The M12 lenses are perfect for the board-level cameras, and it’s cost-effective for lower-end products. The Raspberry Pi camera, on the other hand, comes with nearly no support of interchangeable lenses, and all customers are stuck with the stock lens, which is around 60 degrees horizontal. Therefore, it’s natural for introducing the m12 lens system to the Raspberry Pi for more versatility in the angles of view.