Chinon — 50mm f/1.4 fast standard prime for M42 screw-mount and Pentax K SLR bodies
Chinon Industries built the 50mm f/1.4 as the fast standard prime in its lens range through the 1970s and 1980s, above the more common Auto Chinon 50mm f/1.7 and f/1.9 kit lenses sold with bodies like the CE Memotron and CE-4, and also rebadged as Revuenon and Agfa Color for other retailers.
It was made in M42 screw mount alongside a Pentax K version matching Chinon's 1980 shift to bayonet bodies. Specification sheets credit it with 7 elements in 6 groups (one source disputes this), a 6-blade diaphragm from f/1.4 to f/22, a 49mm filter thread, 0.45m minimum focus and about 245g weight.
Wide open it rendered with lower contrast and a soft, somewhat busy out-of-focus look, tightening up by f/2.8. Whether Chinon built this formula in-house or sourced it from another optical maker remains disputed, and it is generally viewed as a budget alternative to period first-party 50mm f/1.4 optics.
As a common independent-era lens, it usually sells cheaply on the UK used market. Check for the oily, sticky aperture blades often reported on Chinon Auto lenses of this age, confirm the diaphragm and mount coupling move freely, and test the focus helicoid, which often turns stiff after decades of storage.