N°106026 · Family detail
PentaxWide·PENTAX K mount·1975
Pentax SMC 20mm F/4
Specifications01
MountPENTAX K
Focal length20mm
Max aperturef/4
TypeWide · Prime
Release year1975
Weight300 g
Filter size58 mm
Physical length57 mm
Min focus distance0.25 m
Max magnification0.12
Aperture blades5
Optical elements12
Groups10
Min aperturef/22
AutofocusNo
StabilizationNo
Aperture controlAperture ring (Manual settings only)
Lens hoodPH-S58 - Clamp-on rectangular
EraFilm era
Production statusDiscontinued
Additional Info02
ModelSMC
FormatFull-Frame
SeriesK Series Prime
Squeezenone
Lens TypeUltra-wide angle prime lens
Iris Blades5
Release Date1975
Data Protocolnone
Focus Zoom Rodnone
Front Diameter Mm63
Summary02
20mm f/4 prime lens for Pentax K-mount cameras, suitable for wide-angle landscape and general photography. Fixed focal length with a moderate maximum aperture for everyday light levels.
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.