Pentax SMC-FA 31mm f/1.8 AL Limited - Review / Test Report
Lens Reviews - Pentax

Review by Klaus Schroiff, published May 2007

Special thanks to Rüdiger Neumann for providing this lens!


The Pentax SMC FA 31mm f/1.8 AL Limited is the most pronounced wide angle of classic FA Limited lenses. Similar to its cousins it offers an absolutely superb build quality ... at a price (900-1000€/US$). However, to be fair the ultra-large aperture (for a wide-angle lens) is also off the mainstream and quality simply doesn't come for free. Typical for all FA lenses it supports the full 35mm format so it can be used both on film and digital SLRs. On the Pentax K10D its field-of-view is equivalent to about 47mm (full format) so within this scope the lens gets transformed to a "normal" lens.

The build quality of the lens is exceptional with all parts made of metal. The small focus ring operates very smooth and slightly damped. Typical for FA-type lenses there's still a dedicated aperture ring on the lens. The FA 31mm f/1.8 extends a little when focusing towards close distances. Pentax also implemented a built-in flower shaped hood which cannot be removed nor would this be desirable regarding its small size. The lens is/was available both in a silver- and black-colored variant. Unlike its cousins it isn't really a small nor overly light-weight lens.

The FA 31mm f/1.8 has no internal AF motor and relies on a slotted drive screw operated by the camera. As a result AF operation will generate a moderate degree of noise. The AF speed is very fast on the K10D.

Equiv. focal length47 mm (full format equivalent)
Equiv. aperturef/2.7 (full format equivalent, in terms of depth-of-field)
Optical construction9 elements in 7 groups inc. 1 aspherical, 1 ED and 1 HRLD element
Number of aperture blades9
min. focus distance0.3 m (max. magnification ratio 1:6.25)
Dimensions65 x 69 mm
Weight345 g
Filter size58 mm (non-rotating)
Hoodbuilt-in, flower-shaped
Other features-

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