Pentax-D FA 21mm f/2.4 Review: A Great Lens with Poor Camera Support

Pentax-D FA 21mm f/2.4 . review

If you’ve been looking for an ultra-wide lens for a Pentax lately, you’ll likely come across the $1,400 Pentax-D FA 21mm f/2.4 lens that was announced late last year. Whether you should buy it or not depends on how much you like Pentax.

The new 21mm f/2.4 lens gives Pentax users a convenient partner to the FA’s limited range of lenses (31mm f/1.8 and 43mm f/1.9) and can work well across a wide number of use cases including candid portraits of family, friends or business Architectural, landscape, astrophotography or even as a general street photography lens.

While there are other “faster” lenses with similar focal lengths, few are compact, lightweight, powerful and don’t offer a modern design to show off. While the lens isn’t cheap, for hardcore Pentax fans, it’s unique enough to at least warrant a driving experience. Those who end up buying it, however, are probably just the most discerning of the Pentaxians since the lens doesn’t test particularly well, despite what appears to be an outstanding performance. The company’s latest full-frame camera lingers on and it doesn’t seem to be able to keep up with the new optics.

Build quality and design

The Pentax 21mm f/2.4 lens is a very stylish optical with a durable, rigid, weatherproof aluminum body. While the lens lacks an aperture control ring, there is a large manual focus ring with a large display for the focus range/distance scale. Weighing just 416 grams and measuring 3.5 inches long (2.9 inches in diameter), it’s a bit heavier on the back side of the lens which makes it well balanced when mounted on a body like the K-1 Mark II. The lens itself is available in two versions: either black (which I tested) or the “antique” silver design for those looking for something with a stronger retro vibe.

Pentax 21mm front view

The lens elements consist of four ED elements and an ED glass element that the company says work together to provide the absolute minimum possible chromatic aberration and fringing. There is a built-in lens cap on the lens that is permanently attached to the lens body, and at first glance, there appears to be no way to connect a filter system such as a circular polarizer (CPL) or neutral density (ND). The good news is that the Limited FA lens actually has a small 67mm filter thread inside the hood making it easier to install and adjust from the left and right side of the barrel.

The other thing I particularly enjoyed was the focus ring which was smooth and had quite a bit of focus. It has physical limits to the maximum and minimum focus distance which I feel makes transitions fast and accurate; The limited range of the focus ring makes it possible to make quick adjustments from any end with just one finger.

Performance and ease of use

Shooting manually, the lens is easy to use as the focus is very easy and quick to pull from one end to the other. I was able to accurately dial into the focus area I was looking for. While the lens and images were great when shooting manually, autofocus seemed to suffer a bit when it was intended to capture people or objects in a wider scene.

I tested this lens during a game of hockey and some busy street scenes and the autofocus (on a K-1 Mark II body) tends to try to capture the “wider scene” rather than the people moving through it. Not showing alone here, a brief search indicates that other users have also experienced this problem, and a firmware update for this particular camera might fix the problem. This issue isn’t a “lens” issue, apparently, but it’s worth noting for anyone interested in this lens planning to use it with a K-1 Mark II body.

Hockey player wide-angle shot with lost focus

While the autofocus wasn’t as fast on this lens as I would have liked, it was very easy to manually dial in focus with the focus ring. And while I wasn’t always a fan of its performance, the autofocus motor on this lens was incredibly quiet, making it perfectly usable for video shooting.

I noticed while doing some general testing that when shooting outdoors in daylight and “center-balanced” on the exposure meter, the photos tended to be overexposed, and I needed to reduce the highlights or exposure just a bit to get a well-balanced image. I’ve actually found that dialing the exposure compensation dial down to -03 on the camera seems to set things up a bit better there.

This is likely a problem with the camera and not the lens, but given that Pentax does not have the latest full-frame camera and this is a full-frame lens, these issues are unfortunate and inevitable.

For general use, using the lens on various subjects from wide landscapes to close-up shots and even portraits of my dog, it felt as though it was better suited for telephoto targets due to the amazing fall when used in a wide open position. Vignetting was quite intense at f/2.4, but the bokeh and separation from foreground and background were quite nice, even at what many might consider boring settings.

Pentax 21mm f/2.4 dog close-up - bokeh test 1

Pentax 21mm f/2.4 dog close-up - bokeh test 1

picture quality

Pentax says the FA 21mm f/2.4 lens is the first of its kind optimized for digital photography with an advanced optical design that delivers edge-to-edge sharpness. Honestly, for a 21mm lens, I was surprised how little distortion there is around the extreme edges. There was certainly some severe vignetting in the corners when shooting with a wide aperture at f/2.4 which tapers off slowly until around f/5.6. But realistically, this is only a potential problem and it can be easily fixed in the post using most editors and some tweaks to the lens profile settings.

As mentioned above, the bokeh and separation when surface shooting are very nice with a very fast and visually pleasing drop between the subject and the background. Regardless of the aperture, targets in the frame are consistently sharp with very little distortion (hardly noticeable unless specifically searched for). In fact, no lens profiles were applied and no distortion adjustments were made to any of the images included in this review.

Pentax - 21 mm - f2.4 - aperture - Gif

When shooting with f/8 and higher it tends to lose some of the “personality” that the FA 21mm lens offers, but when used in the right settings like urban areas, streets and landscapes, the results speak for themselves. Users are left with clean, sharp images with incredibly vibrant colors with minimal flare or fringing.

Highway Long Exposure with Pentax 21mm Lens

Pentax 21mm f/2.4 sunset view

Here are some sample photos taken with the lens.

Great lens with poor camera support

The Pentax-D FA 21mm f/2.4 lens is designed to deliver a distinctive signature in both far and close subjects and it delivers. Although it may not have been well tested, it left me incredibly flattering images and fits in nicely with the rest of the FA’s limited range of lenses providing users of this series of lenses with a very wide variety of primes.

During my testing period with this system, it became clear why and how Pentax shooters would fall in love with it and the rest of the FA lineup. The new 21mm lens is part of the Pentax system’s esteemed series of lenses that its users have dubbed “jewels” and for good reason. It offers users a slightly wider than usual focal length of wide, but not too wide, which makes it suitable for a variety of situations as well as a lens for everyday general use and has a distinctive optical character when shooting with a wide aperture which is very pleasing and pleasing to the eye.

I think what puts this lens in an odd and excited place is that the Pentax doesn’t have a particularly great full-frame DSLR, at least not in my opinion. The things that caused this lens to sag can be blamed squarely on the aging K-1 Mark II. I’d much rather test this lens on a very good Pentax K-3 Mark III, but this is not a full frame camera, so this lens wouldn’t give its best view.

It’s a bewildering situation which means that even among Pentax shooters – which there aren’t many when compared to the likes of Nikon, Canon and Sony – this lens is made for only a fraction. This fits right inside a niche, and puts the 21mm f/1.4 into a sort of “collector” space for me so that Pentax can correct the camera aspect of this equation.

Pentax 21mm f/2.4 top view

Are there alternatives?

Fortunately, there are several lenses available for those looking for something less expensive in a similar focal range, including the Pentax 21mm f/3.2 AL for $496, the Pentax DA 35mm f/2.4 AL lens for $146, or the Pentax D lens Closer priced FA 15-30mm f/2.8 ED SDM WR Lens for $1,347 is larger and heavier but offers a wider focal range to choose from if you don’t want to be restricted to a prime lens.

Additionally, users can look into third-party Pentax lenses with lenses like the Sigma 30mm f/1.4 DC HSM Art for $499.

Should you buy it?

maybe. For full-frame Pentax shooters who already have other lenses in the FA Limited range, the $1,400 addition of the Pentax-D FA 21mm f/2.4 would be a welcome addition, as it’s a great lens they are sure to love. But, objectively speaking, it doesn’t perform at a level that matches its asking price because the older Pentax’s K-1 Mark II seems ill-equipped to handle premium optics.

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