Pentacon's auto 50mm f/1.8 — a common, characterful East German M42 standard prime.
The Pentacon auto 50mm f/1.8 is an East German standard prime made in M42 mount from the early 1970s. Produced by the Pentacon combine in Dresden, it descended from the Meyer-Optik Oreston 50mm design and was one of the most widely produced standard lenses of the M42 era.
This is a manual-focus M42 screw-mount lens with a 50mm focal length and a maximum aperture of f/1.8, with an automatic diaphragm marked by the auto designation. Focus and aperture are set by hand on the barrel and it is a compact all-metal standard prime. Detailed element figures are not asserted here beyond the verified focal length and aperture.
As a fast standard the 50mm f/1.8 suits portraits, street and general work, with the bright aperture giving low-light capability and shallow depth of field. Descended from the Oreston, it renders with characterful out-of-focus areas that some copies show as a mild swirl, giving images an appealing vintage East German look.
Used copies are very common and inexpensive, one of the easiest M42 standards to find. Inspect for haze, fungus and cleaning marks, confirm the aperture blades are clean and oil-free, a known weak point on these lenses, and check the aperture-ring and focus feel. Verify the M42 mount. An M42 adapter makes it a cheap, characterful standard on mirrorless.