SMC Pentax-FA 31mm F1.8 AL Limited

Construction and Handling

The SMC PENTAX FA 31mm F1.8 AL Limited is a prime of moderate size. It is larger than a pancake lens, or even its 77mm sibling, but still more compact than any zoom. Considering its fast aperture and full frame coverage, the 31mm is actually smaller than many would expect and significantly more compact than comparable lenses from third-party manufacturers.

This section will give you a complete tour of the lens, from every angle. You will also see the lens alongside other comparable lenses and mounted on various camera bodies.

Front Element

The front of the lens is dominated by the large front element and metal rings surrounding it. There are no marks or indications at the front.

Optical elements use Pentax’s well-regarded SMC “Ghostless” coatings. Being a film-era design, it does not take advantage of the newer HD coatings or the Super Protect.

The lens uses a reasonable 58mm filter thread. This diameter is common, although many small Pentax primes use either 52mm or 49mm.

The lens cap is a very elegant metal push-on cap. The inside is covered with smooth felt. Many Limited lenses use a variation of this design.

Lens Body

The body of the lens is made entirely of metal. Like other Limited lenses, especially the three FA, the 31mm is outstanding. Its appearance suggests that it is a premium product. The build quality is impressive, the metal deeply engraved and the assembly tight. There is no wobble, no loose parts and the lettering is easy to read with colored accents.

Starting from the base (at the lens mount) and going up, we first see the aperture ring. This rings features ribs that are a constant of high-end Pentax primes such as the DA Limited and D FA 100mm F2.8 macro. Right above is the depth of field scale. This one bears 6 aperture values, which means that it can actually be useful for manual shooters, in addition to adding a touch of class to the lens. To the right of the scale is a green dot helping to align the lens for mounting.

Above this is the focus distance window, with markings in meters and feet. The text is yellow for meters and light blue for feet. It gives good contrast and is easy to read. Right above is the focus ring, again using the ribbed texture mentioned earlier.

The next element on the lens body is the name of the lens. Engraved in white except for the word “Limited” in red, it takes up a good part of the circumference.

The last item is the permanently attached lens hood.

The back of the lens shows the serial number and large CE identification.

The lens extends slightly when focusing at close distances.

Aperture

The Pentax 31mm uses 9 straight aperture blades.

Lens Mount

The lens mount is metal. Anything else (namely, plastic) would be surprising at this price point. There are no protections against water ingress.

Lens Hood

The lens incorporates a permanent lens hood. The hood is wider than the main body of the lens. It allows the use of filters given that it is made of two bands on the top and bottom, with little or no material to the sides. Since it is not a cylinder, it is referred to as a petal-shape, although this is not strictly the case.

Compared to Other Lenses

Here is the FA 31mm Limited next to its two siblings, the FA 43mm Limited and FA 77mm Limited. The 31mm is the largest of the trio.

Mounted on Camera

Below are images of the 31mm mounted on a Pentax K-1 (full frame) and a Pentax K-3 (APS-C). The lens looks perfectly at home on the either bodies.

Verdict

The Pentax FA 31mm F1.8 Limited is superbly crafted and assembled. The lens follows (or leads) the same design cues as the other Limited: small size, metal construction, engraved markings, elegant touches up to the lens cap. The Limited lenses have sometimes been called jewels, and while the word might be strong, it is obvious why some people feel this passionately about the looks of the FA 31mm and its siblings.