Table of Contents
Pentax-M SMC 120mm f/2.8
Summary
The SMC Pentax-M 120mm f/2.8 is a compact manual-focus telephoto prime introduced in 1977 as part of the second-generation M-series for the Pentax K-mount. It replaced the earlier K-series 120mm f/2.8, offering a lighter, more compact design while retaining the same focal length and optical formula. With its slightly unusual focal length, it sits between the more common 100mm and 135mm lenses, making it a distinctive choice for portraiture, travel, and compressed landscape scenes. Optically, the lens features a 5-element, 5-group design with Super Multi-Coating (SMC) and an 8-blade automatic diaphragm, stopping down to f/32. It focuses as close as 1.2 meters, delivers a 0.13× magnification ratio, and uses a 49mm filter thread. The lens weighs just 270g, measures 63 × 63mm, and includes a built-in slide-out hood—a hallmark of M-series telephotos. There’s no internal focusing or “A” setting on the aperture ring, so metering on modern digital bodies requires stop-down operation.
Tech Specs
| Manufacturer | Pentax |
| Series | M Series Prime |
| Model | SMC |
| Focal Length | 120mm |
| Max Aperture | f/2.8 |
| Min Aperture | f/32 |
| Format | Full-Frame |
| Image Circle | - |
| Minimum Focus | 120cm |
| Focus Rotation | ° |
| Iris Blades | 8 |
| Optical Design | 5/5 |
| Squeeze | none |
| Front Diameter | 63mm |
| Filter Thread | 49mm |
| Focus/Zoom Rod | none |
| Native Mount | Pentax K |
| Data Protocol | none |
| Length | 63mm |
| Weight | 270g |
| Body Telescope | - |
| Body Material | - |
| Focus Drive | - |
| Iris Drive | - |
| Zoom Drive | - |
History
Country of Origin:
Release Date: 1977
Launch Price:
Design Revisions: