Table of Contents
Pentax-M SMC 28-50mm f/3.5-4.5
Summary
The SMC Pentax-M 28-50mm f/3.5-4.5 is a compact manual-focus zoom introduced in 1979 for the Pentax K-mount, produced until 1985. It was designed as a lightweight, walkaround lens for film SLRs, offering a modest but useful range from wide-angle to normal. Though it shares its optical formula with the earlier K-series version, the M-series update brought a more compact barrel and styling to match the smaller M-series bodies like the ME Super and MX. Optically, it uses a 10-element, 10-group design with Super Multi-Coating (SMC) and a 6-blade automatic diaphragm, stopping down to f/22–32 depending on focal length. The lens focuses as close as 60cm, offers a 52mm filter thread, and weighs just 310g, measuring 65 × 52mm. It lacks internal focusing or an “A” setting on the aperture ring, so it’s best suited for manual or aperture-priority shooting. The front element rotates during focusing, which complicates polarizer use, and it was typically paired with a PH-R52 clip-on hood and a dedicated hard case.
Tech Specs
| Manufacturer | Pentax |
| Series | M Series Zoom |
| Model | SMC |
| Focal Length | 28-50mm |
| Max Aperture | f/3.5-4.5 |
| Min Aperture | f/22-32 |
| Format | Full-Frame |
| Image Circle | - |
| Minimum Focus | 60cm |
| Focus Rotation | ° |
| Iris Blades | 6 |
| Optical Design | 10/10 |
| Squeeze | none |
| Front Diameter | 65mm |
| Filter Thread | 52mm |
| Focus/Zoom Rod | none |
| Native Mount | Pentax K |
| Data Protocol | none |
| Length | 52mm |
| Weight | 310g |
| Body Telescope | - |
| Body Material | - |
| Focus Drive | - |
| Iris Drive | - |
| Zoom Drive | - |
History
Country of Origin:
Release Date: 1979
Launch Price:
Design Revisions: