Photo: Nagarazoku (CC BY-SA 2.0)
Quick answer
The Pentax SMC Pentax-FA 31mm 1:1.8 AL Limited is a wide-angle prime lens covering 31mm at f/1.8 for the Pentax K mount. Its fast maximum aperture helps in dim light and gives good subject separation.
About this lens
A 31mm f/1.8 fast wide-angle prime lens, the Pentax SMC Pentax-FA 31mm 1:1.8 AL Limited is designed for Pentax K mount bodies. A compact, metal-bodied Limited-series prime for Pentax K-mount cameras.
Pentax SMC Pentax-FA 31mm 1:1.8 AL Limited specifications
- Brand
- Pentax
- Mount
- Pentax K
- Focal length
- 31mm
- Maximum aperture
- f/1.8
- Lens type
- Prime
- Format coverage
- full-frame
- Optical construction
- 9 elements in 7 groups
- Aperture blades
- 9
- Autofocus motor
- screw-drive
- Minimum focus distance
- 0.3 m
- Maximum magnification
- 0.16x
- Filter thread
- 58 mm
- Weight
- 350 g
- Length
- 69 mm
- Diameter
- 66 mm
Specification source: en.wikipedia.org
What can you shoot with the Pentax SMC Pentax-FA 31mm 1:1.8 AL Limited?
At 31mm this is a wide-angle prime, which typically suits:
- Landscapes and cityscapes
- Street and travel photography
- Environmental portraits and interiors
Its fast maximum aperture helps in dim light and gives good subject separation.
Full-frame equivalent and field of view
Calculated from the focal length and crop factor. Not measured.
| Sensor | Crop | Equivalent | Horizontal FOV | Diagonal FOV |
|---|---|---|---|---|
| Full frame | 1.0x | 31mm | 60.3° | 69.8° |
| APS-C | 1.5x | 47mm | 42.3° | 49.9° |
Frequently asked questions
What mount does the Pentax SMC Pentax-FA 31mm 1:1.8 AL Limited use?
It uses the Pentax K mount, so it fits Pentax K cameras directly.
What is the focal length of the Pentax SMC Pentax-FA 31mm 1:1.8 AL Limited?
It is a fixed 31mm lens with a maximum aperture of f/1.8. That makes it a wide-angle lens.
Is the Pentax SMC Pentax-FA 31mm 1:1.8 AL Limited a prime or a zoom lens?
It is a prime lens with a fixed 31mm focal length. Primes usually open wider than zooms; this one opens to f/1.8.
What is the Pentax SMC Pentax-FA 31mm 1:1.8 AL Limited equivalent on a crop sensor?
On APS-C (1.5x crop) it frames like 47mm on full frame, with a 42.3° horizontal and 49.9° diagonal field of view. These figures are calculated from the focal length and crop factor.
Which cameras does the Pentax SMC Pentax-FA 31mm 1:1.8 AL Limited fit?
Any Pentax K-mount camera, including Pentax K-1, Pentax K-3, Pentax K-3 II, Pentax K-3 Mark III, and Pentax K-30 and 15 more.
Alternatives for Pentax K from other brands
All Pentax K lensesSame mount, overlapping focal range, closest maximum aperture first.
