Table of Contents
Pentax-A SMC 100mm f/2.8 Macro
Summary
The SMC Pentax-A 100mm f/2.8 Macro is a rare and highly regarded manual-focus macro lens introduced in 1985 and produced until 1989, designed for full-frame K-mount film cameras. It was Pentax’s first 100mm macro to offer a 1:1 reproduction ratio and a bright f/2.8 aperture, making it a standout in the A-series lineup. Optically, it features a 7-element/7-group design, Super Multi-Coating (SMC), and an 8-blade automatic diaphragm, delivering a 24° diagonal field of view on full-frame (or ~16° on APS-C). The lens focuses down to 31cm, achieving true life-size magnification, and uses a 58mm filter thread. It weighs 470g, measures 74 × 93mm, and includes a recessed front element that often eliminates the need for a hood. It has an “A” setting on the aperture ring, enabling full program and shutter-priority automation on compatible Pentax bodies.
Tech Specs
| Manufacturer | Pentax |
| Series | A Series Macro |
| Model | SMC |
| Focal Length | 100mm |
| Max Aperture | f/2.8 |
| Min Aperture | f/22 |
| Format | Full-Frame |
| Image Circle | - |
| Minimum Focus | 31cm |
| Focus Rotation | ° |
| Iris Blades | 8 |
| Optical Design | 7/7 |
| Squeeze | none |
| Front Diameter | 74mm |
| Filter Thread | 58mm |
| Focus/Zoom Rod | none |
| Native Mount | Pentax K |
| Data Protocol | none |
| Length | 93mm |
| Weight | 470g |
| Body Telescope | - |
| Body Material | - |
| Focus Drive | - |
| Iris Drive | - |
| Zoom Drive | - |
History
Country of Origin:
Release Date: 1985
Launch Price:
Design Revisions: