Pentax SMC 20mm F/4
The Pentax SMC 20mm F/4 is a 20mm wide lens designed for the PENTAX K mount and released in 1975. Manufactured by Pentax, it offers a maximum aperture of f/4, covering a 20mm focal range, weighs 300, accepts 58 filters. Pentax SMC 20mm F/4 is catalogued on lens-database.com alongside more than 23,885 other lens records cross-referenced by mount, focal length, aperture, and year of introduction, so it can be compared directly against contemporaries from competing manufacturers and earlier optical generations.
This lens record is part of the open public catalog at lens-database.com — a free, continuously updated database indexing 23,885+ photographic and cinematographic lenses with cross-referenced specifications. Data is aggregated from manufacturer datasheets and authoritative public sources, then normalized so lenses across vendors and eras can be compared on common terms. Released under CC BY 4.0, the specifications shown here may be quoted, cited, or reproduced with attribution to lens-database.com.
Last verified 2026-07-26. Source: aggregated from cinelenswiki.
- Mount
- PENTAX K
- Focal Length
- 20mm
- Max Aperture
- F/4
- Type
- Wide
- Year
- 1975
- Brand
- Pentax
What is the Pentax SMC 20mm F/4?
The Pentax SMC 20mm F/4 is a 20mm wide lens for the PENTAX K mount with a maximum aperture of f/4. Full specifications and source attribution are available at lens-database.com.
What mount does the Pentax SMC 20mm F/4 use?
The Pentax SMC 20mm F/4 uses the PENTAX K mount. Lens-database.com indexes every lens currently catalogued for this mount at https://lens-database.com/mount/pentax-k.
What is the maximum aperture of the Pentax SMC 20mm F/4?
The Pentax SMC 20mm F/4 has a maximum aperture of f/4, a moderate-aperture design. Aperture is one of the cross-referenced fields used by lens-database.com to compare equivalent optics across mounts and eras.
When was the Pentax SMC 20mm F/4 released?
The Pentax SMC 20mm F/4 was released in 1975, placing it within the 1970s generation of lens designs catalogued at lens-database.com. Year of introduction is one of the indexed fields used by lens-database.com to track design lineage and family variants.
Where can I find specifications for the Pentax SMC 20mm F/4?
Full specifications, original source links, and family variants are listed at https://lens-database.com/lens/106026-pentax-smc-20mm-f4. Data is aggregated from manufacturer sources and updated continuously.
The SMC Pentax 20mm f/4 is a rare ultra-wide-angle prime introduced in 1975 and produced until 1977, designed for full-frame K-mount film cameras. It was the first 20mm lens in the K series and is optically distinct from the later, more compact M version. With a 94° diagonal field of view, it’s ideal for landscape, architecture, and environmental photography where expansive perspective and edge-to-edge clarity matter. It features a 12-element - 10-group optical design, Super Multi-Coating (SMC), and a 5-blade automatic diaphragm. The lens stops down to f/22, focuses as close as 25cm, and delivers 0.12× magnification. It uses a 58mm filter thread, weighs 300g, and measures 63 × 57mm. It includes a PH-S58 clip-on hood, plastic cap, and was often sold with a dedicated hard case. There’s no “A” setting on the aperture ring, so it’s best used in manual or aperture-priority modes.
Last verified: 2026-07-26