Viltrox AF 13mm f/1.4 STM XF Lens Review: Great Lens, Better Price

The Viltrox AF 13mm f/1.4 STM lens slots neatly into an existing range of Viltrox primes for APS-C cameras, a focal length that is notably absent from Fujifilm directly. The 13mm, which is equivalent to 20mm on 35mm full-frame, is fairly wide and works well for landscapes or architecture, especially for the low price of $429.

Viltrox has built a solid reputation over the last decade as a company that provides quality optics at low cost. It has expanded from manual focus offerings at core focal lengths full autofocus models that are more esoteric and – to – across a great number of mounts.

Viltrox is a China-based photography company that has been making accessories since 2009, including lenses, LEDs, and video monitors. The raison d’etre of the new breed of photography startups — Chinese — is to offer the near-latest technology at significantly lower prices than the named brands. Long gone are the low-quality, low-tech, accessories of yesteryear, replaced with much more modern designs and materials.

For Viltrox’s lenses, it wisely opted to begin its range with simple optical designs that are available to the largest possible market. This has meant targeting full-frame Sony E-mount and APS-C Fuji X-mount models, however, it is also expanding into the Nikon Z-mount and Canon RF-mount, although more on that later. It exclusively focuses on primes as they are simpler to design and manufacture; it’s also arguable that they are more popular with pros and discerning amateurs where profit margins are higher.

The AF 13mm f/1.4 STM, which was announced in January with two additional mounts added in June, slots neatly into an existing range or Viltrox primes that includes 85mm, 56mm, 33mm, and 23mm; remember that these are APS-C lenses so a 1.5x crop factor gives 35mm equivalents of 128mm, 84mm, 50mm, and 35mm. The 13mm, therefore, rounds out this range with a 20mm equivalent. It’s an interesting focal length to choose as the fairly wide 13mm inevitably makes for a more complex optical formula.

Viltrox Lenses

So why would you want a 20 mm equivalent? Intriguingly it’s a focal length I have never shot with and don’t have in my camera bag. My “gotos” have always been 24, 35, 50, and 85 mm, with a 14 mm for those more esoterically wide shots that aren’t fisheye. It’s not that 20mm is necessarily uncommon, but it’s one that has never appealed to me as 24mm is short enough, at which point I move down to the 14mm. So has Viltrox made the right decision? That’s a personal choice and, for some, 20mm may well be perfect. Yes, it’s more distorted than 24mm but not disastrously so and could therefore be a good match for landscapes or interior architectural shots, alongside the inevitable vlogging allowing you to get really close to the action.

Build Quality and Design

The lens is constructed of 14 elements in 11 groups, which includes four ED and two aspheric elements and a multi-layer coated, waterproof, front optic. It has a nine-blade aperture, weighs 420 grams, and takes a larger 67mm filter. As it is a fly-by-wire design, it comes with a micro-USB port that allows firmware upgrades which Viltrox has been forthcoming with. Out of the box, there are front and rear lens caps, a cloth case, and a lens hood.

As you can see from the lineup, the Fujifilm 27mm is a svelte pancake lens that really suits the ergonomics of a street camera; the Viltrox 23mm and 56mm look positively DSLR-like in origin by comparison. The 13mm is a step above those in both size and weight.

Viltrox 13mm on Fuji Viltrox 13mm Top Down

While the fairly chunky 56mm f/1.4 weighs in at 260 grams, the 13mm ups that again to 420 grams. This, of course, is expected because of the wide field-of-view and larger (domed) front optic; the lens is 74x90mm as opposed to 65x72mm for the 56mm f/1.4. In short, this is a relatively big lens when put on a more modest camera — such as my X-E3 — so is perhaps better suited to the larger X-Series cameras.

What has been noticeable about all of the Viltrox lenses that I’ve used is the “premium” feel to them, and the 13mm is no different. Metal is extensively used throughout and the machining is of a high standard. For example, the lens hood that reverses onto — and is neatly stowed — the barrel with a reassuring click; everything fits perfectly. In short, the lens feels great in the hand, rather than a plastic creaking, lightweight, budget model. It should be noted that there is no weather sealing, so it doesn’t match the very best in class, although there are internal dust seals with all focusing internal so any dust ingress should be minimized.

Viltrox 13mm Side On

Behind the lens hood is a large ribbed focus ring that is smooth and has nicely weighted resistance to it. After the barrel markings, you then have the clicked aperture ring in one-third stops. This is different to the earlier 56mm and 33mm which were de-clicked; This might suit video shooters (noiseless and smooth exposure change) but I found myself continually knocking the ring which was irritating when shooting stills. At 13mm, this is not a lens you would choose for the bokeh, so perhaps the choice is a pragmatic one to suit as many users as possible.

One final point — and it’s a small thing — there is a red circle to mark lens orientation for attaching to the camera body. This is white on earlier lenses, but strangely I find it much easier to locate!

Image Quality and Performance

On the X-E3 the lens unsurprisingly feels a little front heavy, however not so unduly. It was still pleasant to use, but would be better balanced on a larger camera.

As far as autofocus performance is concerned, I was pleased with the performance. I have my X-E3 set up for single spot focus (the lens also supports eye focus) using the joystick to move the focus point around. This fits the bill for most scenes and I found the stepper motor was quick and accurate at focusing. If anything, this was better than the previous 33mm and 56mm lenses I’ve used; this was perhaps most noticeable in low light where there was little hunting and it failed less often.

Viltrox AF13 Closeup

From my experience, this is a sharp lens, although predictably softer at the edges where you also get greater distortions. Diffraction also inevitably becomes an issue when you stop right down and the lens sweet spot looks to be around f/5.6 to f/8 which is confirmed by Viltrox’s MTF charts. Unusually for such a wide-angle lens, the aperture is wide at f/1.4 (about f/2.1 equivalent) which opens up slightly more unusual applications with astrophotography and greater creative use of bokeh.

Viltrox AF13 Meadow

Viltrox AF13 Utilizing Wide Angle

Viltrox AF13 More Macro

Viltrox MTF

The lens has a competitive minimum focus distance (MFD) of 22 centimeters, with a hyperfocal distance of 57 cm which means everything from 30 cm would be nominally in focus. The f/1.4 aperture can create some surprisingly effective bokeh. This obviously isn’t a bokeh monster, but it can be effective for close subjects. The bokeh itself is smooth and neutral if perhaps neither overly pleasant nor unpleasant.

Viltrox AF13 More Macro Viltrox AF13 More Macro

Flare was handled reasonably well, something that will always be difficult for a wide lens. It goes without saying that you should always use this lens with the supplied lens hood and there’s no excuse given it’s stored on the barrel. Direct on the sun there is a slight reduction in contrast, with flare understandably becoming more problematic at about 45-degreses to the lens although it’s never outrageous and something all shooters would be aware of anyway.

Viltrox 13mm Lens Flare

Great Lens, Great Price

By this point, I haven’t really mentioned the price: $429. That’s remarkably low for the amount of lens you are getting. At 13mm, it’s wider than anything Fujifilm sells and offers a fantastically wide option without going into the realms of severe distortion.

It’s ideally suited to vlogging where you want that sense of breadth, space, and intimacy. Likewise, it would find a home in many stills shooters’ bags where it would excel in landscape, architecture, and astrophotography. If you haven’t shot with a 20mm equivalent lens — regardless of system — then give it a try. You may just find it fits a niche that you had been looking for. Viltrox has also covered a lot of bases here from the quality construction, fast AF, and well-controlled images.

It’s not perfect, inevitably suffering from flare when stopped down and soft corners, particularly at wider apertures. Its sweet spot is around f/8.0 where you can expect to routinely capture quality images. However that f/1.4 maximum aperture will appeal to those in search of light — think to mosh pit or starry sky — while also offering bokeh potential at a wide angle.

Coming back to my earlier point about other lens mounts, Viltrox has taken the unusual step of an Indiego campaign to fund the production of Nikon Z-mount and Sony E-mount APS-C versions of the lens. Some manufacturers (Peak Design is perhaps the most notable) follow this route to decrease the financial risk while gauging the size of the market. It’s an organic way of growing a lens range based upon demand, rather than the likes of Nikon and Canon who gradually build out their ranges based upon perceived need. It also shows that mirrorless APS-C lens designs are alive and kicking with Fuji, Sony, Nikon, and Canon now all in this space.

Are There Alternatives?

Of course there are, although perhaps unusually nothing that is directly comparable in terms of focal length and aperture. Fujifilm has a plethora of lenses, although the closest is the XF 14 mm f/2.8 R — along with 16mm and 18mm variants — while Sigma has also recently released its 16mm f/1.4 for X-mount. That places the Viltrox 13mm in a class of its own, and perhaps that was the intent.

Should You Buy It?

Yes. While I might have questioned the 20mm equivalent focal length at the beginning, it is quite clear that — while maybe not as popular as other focal lengths — there is a market. The lens adds a focal length option that isn’t available in Fujifilm’s first-party lineup and what Viltrox has made here works well, especially for the price.


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