Table of Contents
Pentax-A 645 SMC 80-160mm f/4.5
Summary
The SMC Pentax-A 645 80-160mm f/4.5 is a manual-focus telephoto zoom lens introduced in the mid-1980s for the Pentax 645 medium format system. Covering a focal range equivalent to approximately 63–126mm in 35mm terms, it was designed to bridge the gap between standard and short telephoto primes—making it a flexible option for portraiture, landscape, and general-purpose photography. Though later replaced by the autofocus FA version, the A-series model remains popular for its optical quality, mechanical precision, and affordable price on the used market. Optically, it features an 11-element, 11-group design with Super Multi-Coating (SMC) and an 8-blade automatic diaphragm, stopping down to f/32. The lens focuses as close as 1 meter, delivering a 0.17× magnification ratio, and uses a 77mm filter thread. It weighs 1010g, measures 82.5 × 131mm, and includes a manual aperture ring with an “A” setting, enabling full program and shutter-priority modes on compatible bodies. There’s no internal focusing, and the front element rotates during focusing—making polarizer use a bit cumbersome. A screw-in RH-A hood and S90-160 soft case were typically included.
Tech Specs
| Manufacturer | Pentax |
| Series | Pentax-A |
| Model | 645 SMC |
| Focal Length | 80-160mm |
| Max Aperture | f/4.5 |
| Min Aperture | f/32 |
| Format | 645 film |
| Image Circle | - |
| Minimum Focus | 100cm |
| Focus Rotation | ° |
| Iris Blades | 8 |
| Optical Design | 11/11 |
| Squeeze | none |
| Front Diameter | 82.5mm |
| Filter Thread | 77mm |
| Focus/Zoom Rod | none |
| Native Mount | Pentax 645 |
| Data Protocol | none |
| Length | 131mm |
| Weight | 1010g |
| Body Telescope | - |
| Body Material | - |
| Focus Drive | - |
| Iris Drive | - |
| Zoom Drive | - |
History
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