N°200239 · Family detail
CosinaPortrait·PENTAX K mount·1979
Cosina Cosinon-S 50mm F/2
Specifications01
MountPENTAX K
Focal length50mm
Max aperturef/2
TypePortrait · Prime
Release year1979
Weight165 g
Filter size49 mm
Min focus distance0.5 m
Aperture blades6
Optical elements6
Groups5
AutofocusNo
StabilizationNo
Aperture controlAperture ring (Manual settings only)
EraFilm era
Production statusDiscontinued
Additional Info02
Lens TypeStandard prime lens
Summary02
Cosina Cosinon-S is a 50mm prime lens for the Pentax K mount, with a maximum aperture of f/2. It’s suited to general and portrait use due to the normal focal length and bright aperture.
AI-assisted summary — verify against linked sourcesWhere can this lens be adapted?
The Pentax K mount has a flange distance of 45.46 mm. A plain adapter fits a camera whose flange distance is at least 1.46 mm shorter. How lens adapters work
- Pentax DA and FA J lenses have no aperture ring. Use an adapter with its own aperture control.
- Pentax DA lenses are made for APS-C.
- Sony EAdapter · 27.46 mm
- Canon RFAdapter · 25.46 mm
- Nikon ZAdapter · 29.46 mm
- Fujifilm XAdapter · 27.76 mm
- L-MountAdapter · 25.46 mm
- Micro Four ThirdsAdapter · 26.21 mm
- Fujifilm G (GFX)Adapter · 18.76 mm
- Canon EF-MAdapter · 27.46 mm
- Canon EFAdapter · 1.46 mm
A rear element that sticks out can hit the camera mirror.
No plain adapter reaches infinity focus on: Nikon F.

Other Mounts03
No alternate mounts are indexed for this family yet.