Introduction

About two months ago, Viltrox released a 35mm f/1.7 for APS-C cameras. It seems they’ve been busy, as they’ve now introduced the 25mm f/1.7 in their Air series. Officially named the Viltrox AF 25mm f/1.7 Air STM ASPH IF, it certainly comes with a lot of acronyms to keep track of!

This is an unusual focal length, equivalent to 37.5mm on a full-frame camera—sitting between the classic 35mm and 40mm, both popular choices for everyday and street photography. Let’s take a closer look!

I tested the lens on a Nikon Zfc
You can see this review as a YouTube video here!
Sample images in high resolution here.

Sample Images

Most of the sample images in this review and many more can be found in higher resolution here.

Specifications

Disclosure

Viltrox kindly provided this lens for test and review purposes.

Handling

The Viltrox 25mm f/1.7 features a sleek, minimalist design, with no controls other than its relatively large focus ring. The lens is primarily made of durable hard plastic, while the mounting plate is metal. Weighing just 170 g, it is compact and lightweight, though slightly larger than the recently released Viltrox 35mm f/1.7, which is also part of the Air series.

The focusing system is focus-by-wire, and the focus ring turns very smoothly. The lens features an internal focusing mechanism, meaning it does not change length while focusing, and the front element does not rotate—a benefit for filter users.

The autofocus system uses a stepper motor for precise and accurate focusing. Autofocus is fast and reliable.

The focus ring can be configured to control manual focus, aperture settings, or exposure compensation, or it can be completely disabled.

The metallic mounting plate feature a USB-C port for future firmware updates.

The lens comes with front and rear caps, a sturdy hard plastic petal-shaped lens hood, and a cloth pouch.

Optical Features

Sharpness (Infinity)

For the infinity sharpness test, we look at three areas of the image, centre, mid-frame, and corner, see highlighted areas in the image below!

The lens delivers excellent sharpness in the centre and midframe, with very good sharpness in the corners right from f/1.7. Stopping down further improves sharpness across the frame, reaching peak performance around f/5.6–f/8. At f/11, sharpness softens slightly, and diffraction becomes more noticeable at f/16, though overall performance remains very good

Sharpness (Portrait)

Let’s look at the points of interest for portraits at the portrait distance: the very centre, the centre’s inner periphery  (1/3 rule intersection), and the centre’s outer periphery (1/4th intersection).

At f/1.7, portrait-distance sharpness is very good in the center of the frame. However, it decreases slightly in the inner midframe before improving again towards the outer midframe. By f/2.8, sharpness becomes excellent across the frame.

It seems that this lens can resolve more details than the Nikon Zfc’s sensor can fully capture, or at least it reaches the sensor’s resolving limit. Since the Nikon Zfc lacks an optical low-pass filter, fine patterns in the inner midframe exhibit some moiré.

Sharpness (Close-up)

The Viltrox 25mm f/1.7 has good to very good sharpness wide open at f/1.7 at close-up distance. Closing the aperture to f/2.8 makes the sharpness excellent. The sharpness remains excellent up to f/11 and peaks at f/4 and f/5.6. At f/11 we see a small dip in sharpness due to diffraction, which weakens a little more at f/16.

Lens Distortion

The lens suffers from a mild barrel distortion, which if you want to fix in Lightroom or Photoshop need to apply +6 correction.

Vignetting

This Viltrox lens exhibits noticeable light falloff at f/1.7, which is not unusual for fast normal lenses, but stopping down to f/2.8 significantly reduces vignetting to a negligible level. Further stopping down does not bring any meaningful improvement, as the light distribution is already well-balanced.

• F/1.7: 2.3 EV
• F/2.8: 0.9 EV
• F/4.0: 0.9 EV
• F/5.6: 0.9 EV

Focus Shift & Aberrations

There is some negligible longitudinal chromatic aberration as purple and green fringing at wider aperture, most visible wide open at f/1.7. It gets much better by f/2.8 and at f/4 it is practically gone. At f/5.6 it has completely disappeared. Though, it is so small, even wide open, that you normally do not notice it.

Lateral chromatic aberration is negligible and well-controlled. As you can see in the following uncorrected image, it is hardly noticeable. You might spot it when comparing the uncorrected and corrected versions, but even then, it’s difficult to see.

The lens can be considered as quite good in correcting the chromatic aberrations.

Flare Resistance

Flare resistance appears to be this lens’s Achilles’ heel, as it’s the one area that slightly takes away from its otherwise excellent performance. Unfortunately, it exhibits both veiling and ghosting flare, regardless of whether you’re shooting at wide or small apertures. This is my assessment so far, though—there could be other weaknesses that emerge further down the testing process.

Coma

The good news is that this Viltrox lens doesn’t show much coma, but unfortunately, it suffers from severe astigmatism wide open. Stopping down to f/5.6 helps eliminate it.

Sunstars

An odd number of aperture blades is not ideal for creating sunstars, particularly when they are rounded, as is the case with this Viltrox lens. However, it can produce distinct sunstars at f/16 and moderately distinct ones at f/11. While it achieves this, the resulting stars appear somewhat busy and are not to my personal taste—but that is a subjective matter.

Focus Breathing

Excellent focus breathing control as there is absolutely none to be seen, a welcome news for videographers.

Bokeh

Let’s look at the bokeh itself first.

The bokeh balls are evenly lit, but onion-ring patterns are visible in the specular highlights. While the transitions are generally soft, some areas show slight double edging. Towards the edges and corners of the frame, the bokeh balls take on a cat’s-eye shape.

Now, let’s take a closer look at how the background blur behaves at different distances and in various shooting scenarios.

Short Distance

Mid Distance

Long Distance

Bokeh’s beauty is in the eye of the beholder—in other words, it’s very subjective. To me, the bokeh here isn’t bad, but it’s not exactly to my liking either. It’s a bit of a mixed bag, sometimes tending to look a little busy in certain situations. That said, this is just my personal opinion. Take a look at these images and the sample shots to see how you feel about it.

Conclusion

As shown in the table above, there is not much bad about the Viltrox 25mm f/1.7 Air. While it doesn’t offer top-tier performance in every aspect, it performs well above average, and I would rate it as a very good lens. It delivers impressive value for its price, and Viltrox’s work is commendable. The lens is exceptionally sharp, and the focus breathing is top-class, making it a strong choice for both photography and video. I liked it a lot, though I do wish the bokeh was a bit softer and flare resistance was better. Personally, I prefer a 40mm-equivalent focal length over a 50mm for street and everyday photography, and since this lens comes close to that, it may have influenced my preference. Overall, this is a very good lens on its own and a fantastic value for the price, with only one notable drawback. Together with the Viltrox AF 56mm f/1.7 Air, it makes a great prime set if you prefer primes over zooms.

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Alternatives

Laowa Argus 25mm f/0.95 CF APO
It is the fastest APS-C lens around with very good optical qualites. A manual only lens though, which is a little larger than the reviewed lens and sells at a higher price. If you want the fastest “normal” lens then this is the lens for you.
Buy new: Laowa Store, Amazon (Anywhere) for $399-$549 (Affiliate links)
Buy used: ebay.com, ebay.de, ebay.co.uk from $260 (Affiliate links)

Nikon Z Nikkor 26mm f/2.8
Nikon’s own Z mount lens in this focal length. Optically , a very good lens, even better than the reviewed lens, and much more compact, but more than 1 stop slower and much more expensive.
Buy new: Amazon (Anywhere) for $397 (Affiliate links)
Buy used: ebay.com, ebay.de, ebay.co.uk  from $300 (Affiliate links)

Viltrox 27mm f/1.2 Pro
This another Viltrox lens with fantastic optical performance, also autofocus and about 1 stop faster. It’s much larger though and costs more.
Buy new: Viltrox Store, Amazon (Anywhere) for $578 (Affiliate links)
Buy used: ebay.com, ebay.de, ebay.co.uk  from $415 (Affiliate links)

Viltrox 35mm f/1.7 Air
It is 35mm, but still in the  “normal”/”standard” focal length. It is also a very good lens but with a longer focal length and about the same price. So, in this case you focal length preference should determine the choice.
Buy new: Viltrox Store, Amazon (Anywhere) for $179 (Affiliate links)
Buy used: ebay.com, ebay.de, ebay.co.uk  from $150 (Affiliate links)

TTArtisan 35mm f/1.8 II
It is 35mm, but still in the  “normal”/”standard” focal length. Although a very good lens that I could own and use myself, not really on the same level as the reviewed lens but a lot more affordable.
Buy new: TTArtisan Store, Amazon (Anywhere) for $125 (Affiliate links)
Buy used: ebay.com, ebay.de, ebay.co.uk  from $110 (Affiliate links)

More Sample Images

Most of the sample images in this review and many more can be found in higher resolution here.

#viltrox25air #carrylesscapturemore

Further Reading

• What camera gear and accessories do I use most frequently?
• Review: Laowa Argus 25mm f/0.95 CF APO (APS-C)
• REVIEW: Nikon Z Nikkor 26mm f/2.8
• Review: Viltrox AF 27mm f/1.2 STM ASPH ED IF PRO (APS- C)
• Review: Viltrox AF 35mm f/1.7 XF (APS-C)
• Review: TTArtisan AF 35mm f/1.8 ED II (APS-C)

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Martin

Martin M.H. lives outside Stockholm, Sweden. He is a M.Sc. in Computer Technology but he has been a passionate photographer for over 45 years. He started his photographic adventures when he was thirteen with an Agfamatic pocket camera, which he soon replaced with a Canon rangefinder camera that his mom gave him in his teenages. After that he has been using Canon SLR, Nikon SLR manual focus and Autofocus, Sony mirrorless crop sensor, Nikon DSLR and Nikon Mirrorless. He has photographed any genre he could throughout the years and you can see all kind of images in his portfolio. During the later years though it has been mostly landscape, nature, travel and some street/documentary photography.

Latest posts by Martin (see all)

• REVIEW: Viltrox AF 25mm f/1.7 Air (APS-C) - February 28, 2025
• Review: TTArtisan AF 35mm f/1.8 ED II (APS-C) - February 19, 2025
• TTArtisan 7.5mm f/2 Pro Fisheye – Ultra Wide for Dramatic Views and Ultra Confined Places - January 29, 2025