Helios's 77M-4 50mm f/1.8 — a fast Soviet double-Gauss standard prime with characterful bokeh.
The Helios-77M-4 50mm f/1.8 is a Soviet standard prime from the Helios family, a faster f/1.8 normal lens made for Zenit cameras. While most 77M variants used the Zenit bayonet mount, the lens is part of the same double-Gauss Helios lineage and is frequently adapted and encountered alongside the M42 Helios standards.
This is a manual-focus lens with a 50mm focal length and a maximum aperture of f/1.8, drafted here for M42 use. Focus and aperture are set by hand on the barrel and it is a compact all-metal standard prime. Exact mount details vary by version and element counts are not asserted here beyond the verified focal length and aperture.
As a fast standard the 50mm f/1.8 is a flexible everyday lens for portraits, street and general photography, with the fast aperture giving good low-light performance and shallow depth of field. Helios standards render smoothly with characterful bokeh, and the 77 series is noted for pleasant out-of-focus rendering that appeals to portrait users.
Used copies are inexpensive though buyers must confirm the mount, as many 77M-4 lenses are Zenit-mount rather than M42. Inspect for haze, fungus and cleaning marks, confirm the aperture works cleanly, and check focus. Verify the mount matches your camera or adapter before purchase. An appropriate adapter allows use on mirrorless bodies.