Super Angulon-R 21mm f4 with three cams. Serial number in the 2.44 million range, produced in 1970. Leica catalog number is 11813.
Introduced in 1968 for the Leicaflex SL, this long-selling lens remained in production until 1992. Although it is slower than its f3.4 predecessor, the rear element protrudes far less, eliminating the need for mirror lock-up.
It was originally supplied as a two-cam lens, but from 1977 onward it became a three-cam version. This example has been upgraded from two cams to three.
The first retrofocus lens adopted by Leica, manufactured by Schneider as an OEM product. It features an 8-group 10-element construction. With extensive optical correction using numerous elements, it offers minimal distortion, high resolution, and reduced vignetting, making it an excellent performer.
Minimum focusing distance is 0.2 m, with both feet and meter scales. Filters are mounted by inserting a Series 8.5 filter into the hood or by attaching a 72 mm screw-in filter.

There is a tiny mark on the front edge of the barrel and a faint rub from attaching and removing the hood, but otherwise the exterior shows almost no signs of use and remains very clean.
Fully overhauled in November 2025. The helicoid, which often feels loose, and the aperture ring, which tends to rattle, have both been carefully serviced and now offer a pleasantly damped, smooth operation with just the right amount of torque.
The glass shows no haze or cleaning marks. For an Angulon, which is often prone to hazing, this example is exceptionally clear and crisp.
It comes as a clean, collector-worthy set with the 12506 hood, front and rear caps, and the original matching-number box.