Table of Contents
Pentax SMC 18mm f/3.5
Summary
The SMC Pentax 18mm f/3.5 is a rare, ultra-wide-angle manual-focus prime lens introduced in 1975 and produced until 1985, designed for full-frame K-mount film cameras. It was one of the widest rectilinear lenses in the Pentax K-series lineup and remains notable for its compactness, optical complexity, and built-in filter system. Optically, it features a 12-element/11-group design with Super Multi-Coating (SMC) to reduce flare and improve contrast. The lens has a 5-blade automatic diaphragm, a minimum aperture of f/22, and a minimum focus distance of 25cm, offering 0.09× magnification. It delivers a 100° diagonal field of view on full-frame (or ~77° on APS-C), making it ideal for landscape, architecture, and environmental photography. It uses a 58mm filter thread, weighs 328g, and measures 63 × 61.5mm.
Tech Specs
| Manufacturer | Pentax |
| Series | K Series Prime |
| Model | SMC |
| Focal Length | 18mm |
| Max Aperture | f/3.5 |
| Min Aperture | f/22 |
| Format | Full-Frame |
| Image Circle | - |
| Minimum Focus | 25cm |
| Focus Rotation | ° |
| Iris Blades | 5 |
| Optical Design | 12/11 |
| Squeeze | none |
| Front Diameter | 63mm |
| Filter Thread | 58mm |
| Focus/Zoom Rod | none |
| Native Mount | Pentax K |
| Data Protocol | none |
| Length | 61.5mm |
| Weight | 328g |
| Body Telescope | - |
| Body Material | - |
| Focus Drive | - |
| Iris Drive | - |
| Zoom Drive | - |
History
Country of Origin:
Release Date: 1975
Launch Price:
Design Revisions: