Table of Contents
Pentax-M SMC 40-80mm f/2.8-4
Summary
The SMC Pentax-M 40–80mm f/2.8–4 is a compact, manual-focus zoom lens introduced in 1980 and produced until 1984, designed for full-frame K-mount film SLRs. It offers a relatively fast aperture range for its time and a unique focal length span, making it a curious outlier in the Pentax-M lineup. With a 7-element/7-group optical design, Super Multi-Coating (SMC), and a 7-blade automatic diaphragm, it delivers a 57°–30° diagonal field of view on full-frame (or ~40–20° on APS-C), making it suitable for portraiture, short telephoto, and general-purpose photography. The lens features a macro mode at the 80mm end, enabling close focusing down to 37cm (1:4 magnification), though users note it’s more of a close-up mode than true macro. In standard use, the minimum focus distance is 1.2 meters. It uses a 49mm filter thread, weighs 395g, and measures 66 × 76mm. Autofocus is absent, as expected for the era, and there’s no “A” setting on the aperture ring, so it’s best used in manual or aperture-priority modes on modern digital bodies.
Tech Specs
| Manufacturer | Pentax |
| Series | M Series Zoom |
| Model | SMC |
| Focal Length | 40-80mm |
| Max Aperture | f/2.8-4 |
| Min Aperture | f/22-32 |
| Format | Full-Frame |
| Image Circle | - |
| Minimum Focus | 120cm |
| Focus Rotation | ° |
| Iris Blades | 7 |
| Optical Design | 7/7 |
| Squeeze | none |
| Front Diameter | 66mm |
| Filter Thread | 49mm |
| Focus/Zoom Rod | none |
| Native Mount | Pentax K |
| Data Protocol | none |
| Length | 76mm |
| Weight | 395g |
| Body Telescope | - |
| Body Material | - |
| Focus Drive | - |
| Iris Drive | - |
| Zoom Drive | - |
History
Country of Origin:
Release Date: 1980
Launch Price:
Design Revisions: