The Leica M1 is an uncommon variant of the Leica M2 that omits the M2's rangefinder focusing assembly, self timer, and preview lever. Leitz began production of the M1 in 1959, and made fewer than 9500 copies. The M1 retains the M2's viewfinder, complete with parallax correction, and has permanently illuminated 35mm and 50mm bright lines. You can spot an M1 right away -- the rangefinder window of the M2 is replaced with a small metal plaque marked "M1". 

In its day, the M1 was the least expensive M model. Removing the rangefinder, the defining trait of the M-series Leicas, greatly simplified the camera. Most were purchased for scientific or medical use and attached to microscopes. Lower cost attracted some photographers to add the M1 as a second body for use with wide angle lenses, such as the Leitz 21mm f4, which do not require precise rangefinder focusing due to their depth of field. And unlike the later Leica MD (1965) and MDa (1967), the "blind" Leicas that completely omitted the viewfinder assembly, the M1 provides parallax-corrected framing with a 35mm lens mounted. This versatility saw some M1s purchased by ambitious photographers looking to save where they could on a premium purchase. The M1 is also suitable for use with the extensive Leitz Visoflex system, which converts an M-series camera into a SLR via an externally mounted reflex prism and lenses.

The overall low production of the M1, combined with the fact that Leica chose to entirely remove the viewfinder of its next generation of scientific cameras in the MD and MDa, indicates that there was a small market for this camera's very specific feature set. The few Leica M1s not used in technical applications were mainly marketed and sold to customers who had already bought into the M-system. Leica used M2 boxes for the M1, opting to simply sticker over the "M2." Today, rarity and collectibility make prices for M1s competitive with the fully-featured M2 / M3 / M4 cameras, presenting modern buyers with a similarly difficult proposition.

Outside of its rarity and status compared with other M models, the M1 is a joy to use. It retains all of the tactile engagement of the M2, the quality Leica stands on, and handles beautifully with a compact wide angle lens mounted to it. Paired with a 35mm lens, it makes an excellent street photography kit, its bright rangefinder-less 35mm frame encouraging attention to composition. While the MD and MDa are more affordable M-series cameras to use with ultra wide lenses, the M1 still has a unique allure. The M1's odd and specific set of skills attracts people to it today as it did in the 1960s.