Viltrox AF 25mm f/1.7 Air review: another breath of fresh air for APS-C format cameras

Viltrox won me over with its range of 13mm, 23mm, 33mm and 56mm f/1.4 prime lenses for APS-C format Fujifilm X, Nikon Z and Sony Alpha mirrorless cameras. They’re very smartly turned out with an all metal build that extends to the mounting plate, barrel and hood, and they all feature a de-clicked aperture control ring. Even so, they’re very competitively priced for ‘fast glass’. The Air series of lenses sets its sights a little lower, with a mostly plastic build but still retaining a metal mounting plate, ditching the aperture ring and the aperture ratings are a little slower. The upside is that Viltrox’s Air lenses are designed to be as small and lightweight as possible, while still delivering impressive image quality and all-round performance, at incredibly low-budget prices. From the Air series, I’ve already been impressed with the APS-C format AF 35mm F1.7 Air and AF 56mm F1.7 Air, and the full-frame compatible AF 20mm F2.8 Air and AF 40mm F2.5 Air. The new AF 25mm f/1.7 Air is the fifth in the series, aiming to compete with own-brand prime lenses for the best Fujifilm X, best Nikon Z and best Sony E-mount mirrorless cameras.

Viltrox AF 25mm f/1.7 Air: Specifications

Viltrox AF 25mm f/1.7 Air: Price

Unsurprisingly, the AF 25mm f/1.7 Air sets out to undercut the faster f/1.4 lenses in the Viltrox APS-C format line-up. That’s actually quite a tall order, as the metal-bodied Viltrox AF 23mm F1.4 Z, Viltrox AF 33mm F1.4 Z, and Viltrox AF 56mm F1.4 Z primes currently cost around $239 / £185 / AU$377 each, whereas the slightly larger Viltrox AF 13mm F1.4 Z costs around $486 / £377 / AU$767. Even so, the series of Viltrox Air lenses thus far for both APS-C and full-frame cameras wins out for cost-cutting, all five of them selling for about $179 / £139 / AU$282 each. To give further context to the AF 25mm f/1.7 Air, the Fujifilm XF 27mm f/2.8 R WR costs $399 / £399 / AU$646, the Nikon Z DX 24mm f/1.7 costs $277 / £224 /AU$499 and the Sony E 35mm f/1.8 OSS costs $473 / £325 / AU$698. Suffice it to say that the AF 24mm f/1.7 Air is a seriously affordable lens!

Viltrox AF 25mm f/1.7 Air: Design & Handling

Lenses these days no longer seem to follow convention. For this one, the 25mm focal length isn’t entirely unprecedented but it’s pretty irregular, as is the aperture rating of f/1.7 compared with the likes of f/1.8 and f/1.4 lenses. Take the APS-C crop factor into account and the ‘effective’ focal length of 37.5mm still isn’t exactly ‘normal’. As such, it falls between the highly popular 35mm focal length in full-frame terms, and the 40mm which has become a little more common recently. In a nutshell though, you get a viewing angle of 60 degrees, which I actually found very natural for street photography and general shooting, while testing the lens. It’s a little wider than a standard perspective and pretty similar to using a 35mm lens on a full-frame camera.

Think ‘budget lenses’ and you’re probably thinking ‘low-grade glass’. That certainly doesn’t seem to be the case here. Despite its bargain-basement price tag, the Viltrox features 12 optical elements in total, including one ED (Extra-low Dispersion) element, two aspherical elements and two high-refractive elements. It’s the kind of line-up that I’d expect in a rather more expensive lens.

While the focal length and aperture rating are unconventional, the overall design adheres to the ‘keep it simple’ principle. That helps to keep the size and weight to a minimum and at 64x54mm the lens certainly is small, just over a couple of inches long. It’s also really lightweight at 170g (6 ounces), living up to its ‘Air’ billing. The lens barrel is made from plastic but has a robust and high-quality feel to it. Unlike some own-brand lightweight lenses (including all of the Nikon Z DX format lenses that spring to mind) the Viltrox has a hardened aluminum mounting plate, rather than a plastic plate. The mounting plate also features a USB-C port, which can be used for applying firmware updates if and when required.

The autofocus system is of the lead-screw stepping motor variety, thus combining a decent turn of speed with near-silent operation, and being equally adept for stills and video capture. As usual, the focus ring is electronically coupled but gives good tactile feedback and enables very precise adjustments. Focusing is full internal so the front element neither extends nor rotates. The focus range itself is 0.3m (or about a foot) to infinity, enabling a 0.11x maximum magnification factor at the short end. That’s not bad but it’s certainly not a lens with any macro potential for extreme close-ups.

You can’t expect everything from such a low-budget lens and, unsurprisingly, the Viltrox doesn’t feature any weather-seals. Even so, build quality feels good overall and unlike many own-brand budget lenses from camera manufacturers, it’s supplied with a petal shaped hood and even a carrying pouch.

Viltrox AF 25mm f/1.7 Air: Performance

Buy cheap photographic kit and you’ll often be disappointed with the end results. Following in the footsteps of the previous four Viltrox Air lenses that I’ve reviewed, I was actually highly impressed with the quality of the 25mm. Autofocus isn’t really snappy but it’s certainly quick enough for most needs. More importantly for me, it proved consistently accurate throughout my testing, for everything from close-ups to distant subject matter.

Levels of sharpness are very good, not only in the central region of the image frame but right out to the extreme edges and corners. And that holds true even when shooting wide-open at f/1.7. The lens makes a similarly good job of keeping color fringing to an absolute minimum, as well as keeping ghosting and flare at bay. There’s a slight touch of barrel distortion when uncorrected but it’s fairly minimal and, unlike many compact lenses designed for mirrorless cameras, the Viltrox doesn’t rely on automatic in-camera correction that can’t be disabled.

Naturally, one of the main reasons for buying a relatively ‘fast’ prime lens rather than sticking with a kit zoom lens is to gain a tighter depth of field. It’s ideal when you want to isolate the main subject in a composition by blurring the background. The Viltrox again does well here, combining its good levels of sharpness with fairly smooth bokeh. There’s also very little in the way of axial chromatic aberration (or bokeh fringing) which is often a problem with fast lenses, showing up as color fringing around high-contrast transitions just in front of or behind the plane of focus. All in all, the Viltrox AF 25mm f/1.7 Air is a very good performer.

Viltrox AF 25mm f/1.7 Air: Sample Images

The following gallery of sample shots were taken in bright sunny conditions (and in the shadows) at the Bristol Floating Harbour in the UK. I used a variety of subject matter and aperture settings to demonstrate the sharpness of the lens, as well as the quality of its bokeh.

Image 1 of 11

Viltrox AF 25mm f/1.7 Air: Lab Results

We run a range of lab tests under controlled conditions, using the Imatest Master testing suite. Photos of test charts are taken across the range of apertures and zooms (where available), then analyzed for sharpness, distortion and chromatic aberrations.

We use Imatest SFR (spatial frequency response) charts and analysis software to plot lens resolution at the center of the image frame, corners and mid-point distances, across the range of aperture settings and, with zoom lenses, at four different focal lengths. The tests also measure distortion and color fringing (chromatic aberration).

Sharpness:

Levels of sharpness are both impressive and very consistent throughout almost the entire aperture range. Center-sharpness remains very good wide-open at f/1.7 while apertures of between f/4 and f/8 deliver optimum edge/corner-sharpness. Even so, there’s plenty of corner-sharpness at wider apertures.

Fringing:

There’s very little color fringing even out at the extreme edges and corners of the image frame, throughout the aperture range. It’s almost impossible to spot even with automatic in-camera correction switched off.

Distortion: -1.28

There’s a touch of barrel distortion but it generally goes unnoticed, even in architectural shooting. And as with color fringing, that’s with automatic in-camera correction disabled.

Viltrox AF 25mm f/1.7 Air: Verdict

APS-C format cameras have their own particular advantages over full-frame cameras, two of them typically being a relatively compact and lightweight build, and a lower purchase price. The Viltrox 25mm f/1.7 Air fits in with this seamlessly. It’s refreshingly small with a featherweight construction, making it ideal for street photography and candid shooting. It’s also insanely great value for money with a rock-bottom asking price. All in all, this is one lens that truly punches above its weight and purchase price.

Alternatives

The Viltrox AF 33mm F1.4 Z is a more up-market APS-C format lens with a more classic 50mm effective focal length and f/1.4 aperture rating. It has a full metal construction and features a de-clicked aperture control ring. The selling price is currently around 239 / £185 / AU$377.

The Viltrox AF 27mm f/1.2 Pro has a super-fast f/1.2 aperture rating and a ‘pro’ build that includes weather-seals, an aperture control ring and other handling finery. It’s a fabulous lens but necessarily bigger and heavier than the Air lens. It costs around $578 / £449 / AU$913.