SMC Pentax-M 40mm f/2.8 Lens
The Pentax 40mm f/2.8 is a 40mm f/2.8 lens designed for Pentax K mount cameras. Used copies start from $175 on GearFocus, with buyer protection on every purchase.
SMC Pentax-M 40mm f/2.8 Lens
Used Pentax 40mm f/2.8 Listings on GearFocus
Lens Overview — Pentax 40mm f/2.8
Key Features — Pentax 40mm f/2.8
40mm f/2.8 Prime: A standard focal length with an f/2.8 maximum aperture, offering useful low-light capability and modest background separation in a fixed-focal-length design.
Pentax K Mount: Compatible with the full range of Pentax K-mount film and digital bodies, including modern DSLRs.
Full-Frame Coverage: Projects an image circle large enough for full-frame sensors, making it usable across the entire Pentax K-mount lineup without vignetting.
Manual Focus Only: Fully manual focus operation suits photographers who prefer deliberate, hands-on control over their focus point.
110g Ultra-Lightweight Build: At just 110g, this is one of the lightest lenses available for the Pentax K mount, making it easy to carry for extended periods.
Slim Pancake Profile: The compact, low-profile form factor keeps the overall camera-and-lens package small and unobtrusive.
Lens Specifications — Pentax 40mm f/2.8
| Spec | Detail |
|---|---|
| Use Cases | Portrait, Street, Travel |
| Lens Type | Prime |
| Format | Full Frame |
| Zoom/Prime | Prime |
| Focal Length | 40mm |
| Maximum Aperture | f/2.8 |
| Camera System | DSLR |
| Lens Mount | Pentax K |
| Autofocus | No |
| Focus Type | Manual |
| Image Stabilization | None |
| Filter Thread | 49mm |
Description — Pentax 40mm f/2.8
The SMC Pentax-M 40mm f/2.8 is a prime lens with a Pentax K mount, designed for full-frame coverage and compatible with DSLR camera systems. Its 40mm focal length sits in the standard range, offering a natural perspective well suited to everyday shooting. The f/2.8 maximum aperture provides solid performance in varied lighting and enables some background separation in your images.
Focusing is manual only, giving photographers direct, tactile control over where the lens focuses. At just 110g, this is a remarkably light lens that won't add significant weight to any Pentax K-mount kit. The 49mm filter thread keeps filter accessories affordable and easy to source.
There is no image stabilization, so steady technique or faster shutter speeds are recommended when shooting handheld. For Pentax K-mount photographers looking for a lightweight, no-frills manual prime at a standard focal length, this lens offers a compact and practical option.
Pros — Pentax 40mm f/2.8
- ✓Extremely lightweight at just 110g, ideal for shooters who prioritize portability
- ✓Full-frame coverage means it works across the entire Pentax K-mount camera range
- ✓f/2.8 maximum aperture offers useful low-light capability for a lens of this size
Cons — Pentax 40mm f/2.8
- ✗Manual focus only — no autofocus support for faster or more spontaneous shooting
- ✗No image stabilization, which can be limiting in lower light at slower shutter speeds
- ✗f/2.8 maximum aperture, while usable, is not as fast as some other compact primes in this focal range
Videos — Pentax 40mm f/2.8
Pentax SMC 35mm f2.8 - Vintage Lens — Thomas Fransson