Table of Contents
Pentax-A* SMC 300mm f/4
Summary
The SMC Pentax-A* 300mm f/4 is a premium manual-focus telephoto prime lens introduced in 1984 and produced until 1989, part of Pentax’s elite A* (A-Star) series. Designed for K-mount 35mm and full-frame digital SLRs, it features an 8-element/7-group optical formula with ED (Extra-low Dispersion) glass, though this isn’t marked on the lens itself. It offers a constant f/4 aperture, a minimum focus distance of 4 meters, and a maximum magnification of 0.09×—ideal for wildlife, sports, and astrophotography. The lens includes a built-in sliding hood, a 77mm filter thread, and weighs 850g, measuring 84 × 132mm. The 8-blade automatic diaphragm and Super Multi-Coating (SMC) contribute to its smooth bokeh, excellent contrast, and flare resistance.
Tech Specs
| Manufacturer | Pentax |
| Series | A* Series Prime |
| Model | SMC |
| Focal Length | 300mm |
| Max Aperture | f/4 |
| Min Aperture | f/32 |
| Format | Full-Frame |
| Image Circle | - |
| Minimum Focus | 400cm |
| Focus Rotation | ° |
| Iris Blades | 8 |
| Optical Design | 8/7 |
| Squeeze | none |
| Front Diameter | 84mm |
| Filter Thread | 77mm |
| Focus/Zoom Rod | none |
| Native Mount | Pentax K |
| Data Protocol | none |
| Length | 132mm |
| Weight | 850g |
| Body Telescope | - |
| Body Material | - |
| Focus Drive | - |
| Iris Drive | - |
| Zoom Drive | - |
History
Country of Origin:
Release Date: 1984
Launch Price:
Design Revisions:
Service
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Service Manual: (Insert link to manual here)
Full CLA: TBD hrs.
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Cine-Mod
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Focus Ring O.D.: -
Zoom Ring O.D.: -
Iris Ring O.D.: -
De-click Y/N: -
Additional Notes:
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