Table of Contents
Pentax-M SMC 50mm f/4 Macro
Summary
The SMC Pentax-M 50mm f/4 Macro is a compact, manual-focus macro lens introduced in 1977 and produced until 1984, designed for full-frame K-mount film cameras but fully usable on modern Pentax DSLRs. It features a Tessar-type 4-element/3-group optical design, a 5-blade automatic diaphragm, and Super Multi-Coating (SMC) for improved contrast and flare resistance. With a maximum aperture of f/4 and a minimum aperture of f/32, it’s slower than typical 50mm primes but optimized for flat-field sharpness and close-up work. The lens focuses down to 23cm, delivering 0.45× magnification, and includes engraved reproduction ratios on the barrel—a thoughtful touch for macro shooters. It uses a 49mm filter thread, weighs just 160g, and measures 63 × 42.5mm. The deeply recessed front element often eliminates the need for a hood.
Tech Specs
| Manufacturer | Pentax |
| Series | M Series Macro |
| Model | SMC |
| Focal Length | 50mm |
| Max Aperture | f/4 |
| Min Aperture | f/32 |
| Format | Full-Frame |
| Image Circle | - |
| Minimum Focus | 45cm |
| Focus Rotation | ° |
| Iris Blades | 5 |
| Optical Design | 4/3 |
| Squeeze | none |
| Front Diameter | 63mm |
| Filter Thread | 49mm |
| Focus/Zoom Rod | none |
| Native Mount | Pentax K |
| Data Protocol | none |
| Length | 42.5mm |
| Weight | 160g |
| Body Telescope | - |
| Body Material | - |
| Focus Drive | - |
| Iris Drive | - |
| Zoom Drive | - |
History
Country of Origin:
Release Date: 1977
Launch Price:
Design Revisions: