N°100016 · Family detail
PentaxWide·PENTAX K mount·1985
Smc Pentax-A 20mm F/2.8
Specifications01
MountPENTAX K
Focal length20mm
Max aperturef/2.8
TypeWide · Prime
Release year1985
Weight245 g
Filter size67 mm
Min focus distance0.25 m
Max magnification0.12
Aperture blades5
Optical elements10
Groups9
AutofocusNo
StabilizationNo
Aperture controlAperture ring (Manual settings + Auto Exposure setting)
Lens hoodMH-RB67 - Screw-type round
TeleconvertersPentax Rear Converter-A 1.4X-S→ 28mm F/3.9
Pentax Rear Converter-A 2X-S→ 40mm F/5.6
EraFilm era
Production statusDiscontinued
Additional Info02
Lens TypeUltra-wide angle prime lens
Summary02
Pentax K-mount 20mm prime lens with a fixed f/2.8 maximum aperture. Designed for wide-angle use such as landscapes, interiors, and general photography.
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.