smc Pentax-A 20mm F/2.8
Ultra-wide angle prime lens • Film era • Discontinued
- Announced:
- · February 1985
- Production status:
- ● Discontinued
- Country of design:
- · Japan
- Original name:
- · SMC PENTAX-A 1:2.8 20mm
- Class:
- · Fast full-frame ultra-wide angle prime lens
- · Professional model
- System:
- · Pentax K (1975)
Abbreviations
| SMC | Multi-layer anti-reflection coating is applied to the surfaces of lens elements. This anti-reflection coating increases light transmission, eliminates flare and ghosting, and maintains color consistence among all lens models. |
| A | A manual focus lens with automatic maximum aperture indexing and automatic aperture control. Learn more |
Sample photos (7)
F/2.8
F/2.8
F/2.8
F/2.8
F/2.8
F/2.8
F/2.8
Model history (2)
| ■smc Pentax-A 20mm F/2.8 | A | 10 - 9 | 0.25m | ⌀67 | 1985 ● | |
| ■smc Pentax-FA 20mm F/2.8 | A | 10 - 9 | 0.25m | ⌀67 | 1995 ● | |
Specification
| Optical design: | |
| 35mm full frame | |
| 20mm | |
| F/2.8 | |
| 10 elements in 9 groups | |
| Floating element system | |
| Pentax K [45.5mm] | |
| 94.5° (35mm full frame) | |
| On Pentax K APS-C [1.53x] cameras: | |
35mm equivalent focal length: | 30.6mm (in terms of field of view) |
35mm equivalent speed: | F/4.3 (in terms of depth of field) |
Diagonal angle of view: | 70.5° |
| Diaphragm mechanism: | |
Diaphragm type: | Automatic |
Aperture control: | Aperture ring (Manual settings + Auto Exposure setting) |
| 5 (five) | |
| Focusing: | |
| 0.25m | |
| 1:8.33 | |
Focusing modes: | Manual focus only |
Manual focus control: | Focusing ring |
| Physical characteristics: | |
| 245g | |
| ⌀70×43.5mm | |
| Accessories: | |
| Screw-type 67mm | |
| MH-RB67 - Screw-type round | |
| Pentax Rear Converter-A 1.4X-S → 28mm F/3.9 | |
| Pentax Rear Converter-A 2X-S → 40mm F/5.6 |
Sources of data
- Manufacturer's technical data.
- Pentax 35mm SLR lenses (September 1989).
- Pentax 35mm interchangeable lenses operating manual (August 2003).
- Pentax lenses & accessories booklet (December 1986).
- Pentax 35mm SLR lenses.
- Pentax Z-1P booklet (PUB. 016901) (September 1995).
- Pentax A3 booklet (PUB. 08061) (January 1985).
- Pentax cameras booklet (PUB. 06091, 40 pages) (March 1987).
- Pentax SLR cameras booklet (PUB. 050101) (September 1988).
- Pentax - A complete selection of top-performance cameras booklet (PUB. 040201) (October 1997).
- Pentax ZX-M booklet.
Manufacturer description
This fast f/2.8 wide-angle lens features extended depth of field - perfect for quick candid shots or fast moving subjects - and a convenient viewing angle of 93 degrees. With Pentax original Floating Mechanism, it ensures sharp, stable image quality, even in closeups.
Pentax-A series
The third generation of lenses designed for Pentax 35mm SLR cameras with bayonet mount. Introduced with the Pentax super A in 1983.
- Robust, all-metal design with recessed focusing distance scale;
- Fully automatic diaphragm;
- Support for TTL open-aperture metering;
- Electronic contacts for transmission of aperture information;
- "A" setting on the aperture ring for automatic aperture control in the Programmed AE and Shutter-priority AE modes;
- Extremely accurate manual focusing with rubberized focusing ring;
- Multi-layer anti-reflection coating.
Other ultra-wide angle prime lenses in the Pentax K system
| ■Pentax K mount (5) | |||||||||
| smc Pentax 15mm F/3.5 | A | 13 - 12 | 0.30m | -- | 1975 ● | ||||
| smc Pentax-A 15mm F/3.5 | A | 13 - 12 | 0.30m | -- | 1984 ● | ||||
| smc Pentax 18mm F/3.5 | A | 12 - 11 | 0.25m | -- | 1975 ● | ||||
| smc Pentax 20mm F/4 | A | 12 - 10 | 0.25m | ⌀58 | 1975 ● | ||||
| smc Pentax-M 20mm F/4 | A | 8 - 8 | 0.25m | ⌀49 | 1978 ● | ||||
Lenses with similar focal length
| ■Pentax K mount (25) | |||||||||
| Chinon Auto 17mm F/3.5 MC | A | 11 - 9 | 0.25m | ⌀67 | 1985 ● | ||||
| Cosina Voigtlander Color-Skopar 20mm F/3.5 Aspherical SL II | A | 9 - 6 | 0.20m | ⌀52 | 2009 ● | ||||
| Cosina Wide Angle 20mm F/3.8 MC | A | 9 - 8 | 0.20m | ⌀62 | ● | ||||
| Irix 21mm F/1.4 SLR | A | 15 - 11 | 0.30m | -- | 2022 ● | ||||
| Panagor Auto Wide Angle 21mm F/4 | A | 9 - 7 | 0.16m | ⌀82 | ● | ||||
| Ricoh XR Rikenon 18mm F/2.8 | A | 11 - 9 | 0.25m | ⌀67 | 1982 ● | ||||
| Sigma MF 18mm F/3.5 ZEN | A | 10 - 9 | 0.25m | ⌀72 | 1992 ● | ||||
| Sigma MF Ultra-Wide 18mm F/2.8 Multi-Coated II | A | 10 - 9 | 0.25m | ⌀72 | 1984 ● | ||||
| Sigma MF Ultra-Wide 18mm F/2.8 Multi-Coated | A | 11 - 9 | 0.25m | ⌀67 | 1980 ● | ||||
| Sigma MF 18mm F/2.8 Filtermatic | A | 12 - 9 | 0.23m | ⌀77 | 1978 ● | ||||
| Soligor Wide-Auto 17mm F/3.5 [MC] (s/n 1xxxxxxx) | A | 11 - 8 | 0.22m | ⌀72 | ● | ||||
| Soligor C/D Wide-Auto 20mm F/2.8 MC | A | 9 - 7 | 0.20m | ⌀58 | ● | ||||
| Mir-47K 20mm F/2.5 MC akaМИР-47К 20mm F/2.5 МС | A | 10 - 9 | 0.30m | -- | 1988 ● | ||||
| Zenitar 20mm F/2.8 MC akaЗЕНИТАР-К 20mm F/2.8 МС akaЗЕНИТАР-М 20mm F/2.8 МС akaЗЕНИТАР-Н 20mm F/2.8 МС akaЗЕНИТАР-С 20mm F/2.8 МС | A | 10 - 9 | 0.25m | ⌀67 | ● | ||||
| Spiratone Ultra Wideangle 18mm F/3.5 Pluracoat [I] | A | 11 - 8 | 0.22m | ⌀72 | 1979 ● | ||||
| Spiratone Ultra Wideangle 18mm F/3.5 Pluracoat [II] | A | 11 - 9 | 0.25m | ⌀67 | ● | ||||
| Spiratone 20mm F/2.8 Plura-Coat | A | 9 - 7 | 0.20m | ⌀58 | 1983 ● | ||||
| Tokina 17mm F/3.5 RMC Type 2 akaSpiratone Ultra Wideangle 17mm F/3.5 Pluracoat akaTokina SL 17mm F/3.5 | A | 11 - 9 | 0.25m | ⌀67 | 1980 ● | ||||
| Tokina Wide-Auto 17mm F/3.5 RMC Type 1 | A | 11 - 8 | 0.22m | ⌀72 | ● | ||||
| Vivitar Auto Wide-Angle 20mm F/3.8 (s/n 22xxxxxx) | A | 9 - 7 | 0.15m | ⌀82 | 1969 ● | ||||
| Vivitar Auto Wide-Angle 17mm F/3.5 (s/n 37xxxxxx) | A | 11 - 8 | 0.22m | ⌀72 | 1976 ● | ||||
| Vivitar Wide-Angle 17mm F/3.5 MC (s/n 37xxxxxx) | A | 11 - 9 | 0.25m | ⌀67 | ● | ||||
| Vivitar Wide Angle 19mm F/3.8 MC (s/n 9xxxxxxx) | A | 9 - 8 | 0.20m | ⌀62 | ● | ||||
| Carl Zeiss Classic Distagon T* 18mm F/3.5 ZE / ZF / ZF.2 / ZK | A | 13 - 11 | 0.30m | E82 | 2008 ● | ||||
| Carl Zeiss Classic Distagon T* 21mm F/2.8 ZE / ZF / ZF.2 / ZK | A | 16 - 13 | 0.22m | E82 | 2008 ● | ||||
| ■Interchangeable mount (6) | |||||||||
| Sigma[-XQ] MF [Widerama] 18mm F/3.2 [Multi-Coated] [YS] akaAccura/Sigma 18mm F/3.2 akaSpiratone 18mm F/3.2 akaSpiratone 18mm F/3.5 | A | 12 - 10 | 0.17m | ⌀72 | 1972 ● | ||||
| Soligor Wide-Auto 21mm F/3.8 (s/n 1xxxxxx) [T-4] | A | 9 - 8 | 0.35m | ⌀72 | 1970 ● | ||||
| Tamron SP 17mm F/3.5 51B [Adaptall-2] | A | 12 - 10 | 0.25m | -- | 1979 ● | ||||
| Tamron SP 17mm F/3.5 151B [Adaptall-2] | A | 12 - 10 | 0.25m | -- | 1984 ● | ||||
| Tamron Auto 21mm F/4.5 [Adapt-A-Matic] | A | 8 - 6 | 0.25m | ⌀82 | 1970 ● | ||||
| Vivitar Auto Wide-Angle 21mm F/3.8 (s/n 37xxxxxxx) [T-4] | A | 9 - 8 | 0.35m | ⌀72 | ● | ||||