Intro
In the past, I generally avoided cheaper lenses for the Sony E-mount system. They typically had poor build quality and noticeably bad image performance. However, the past 3–5 years have seen a shift with the introduction of affordable optics from East Asian companies like Viltrox.
The Viltrox 25mm f/1.7 AIR lens is designed for APS-C (crop sensor) cameras like the Sony A6xxx series or the FX30. It’s incredibly compact, minimalistic, and very lightweight. I tested this lens for over a month using my Sony A7CR in crop mode (equivalent to the 26MP sensor from the a6700) and my Sony A1 for video. Viltrox did not send me this lens. I purchased it with my own money.
This lens kicks off my Budget Lens Review series, where I check out lenses under $200 USD and see if they’re actually usable. I’ll also compare these budget options to more expensive premium lenses to see if spending the extra money is really worth it.
Specs
Focal Length: 25mm (37.5mm full-frame equivalent)
Mount: Sony E (Crop Sensor); also available for Fuji X and Nikon Z Mount
Minimum Focus Distance: 30cm (0.3m)
Maximum Aperture: f/1.7
Minimum Aperture: f/16
Optical Construction: 12 elements in 10 groups; 9 diaphragm blades
Weight: 170g
Dimensions (Diameter x Length): 64mm x 54.5mm (2.5" x 2.1")
Filter Size: 52mm
Weather Sealing: None
Price: $176 USD
Build Quality
The Viltrox 25 f/1.7 AIR lens is made entirely out of plastic, which I expected at this price point. Honestly, it is better that it is lightweight because it makes for an excellent travel prime lens.
The design is very simple. There is no aperture ring, no custom buttons, and no AF/MF switch. Just a single focus ring that turns easily, although it is not dampened. Most people will be shooting this lens in autofocus anyway, so the minimal design makes sense.
The aperture stops from f/1.7 to f/16, with a progression through traditional one third stops (for example f/2.2, f/2.5, f/3.2). I have no major complaints about the build quality, but two small things stand out. The lens hood is slightly annoying to attach, and the lack of a weather gasket on the mount is disappointing. Adding a basic rubber seal would not have been an expensive upgrade.
The Viltrox 25 f/1.7 AIR lens includes a USB-C port in the mount of the lens. This is becoming standard with Viltrox’s newer lenses and I’m glad this is starting to become a normal practice. I love when manufacturers plan to support lens performance with future updates rather than the lens being technologically frozen in time upon release.
What’s odd is that the 25 f/1.7 is the one lens that’s missing from Viltrox’s support page. I’m hoping this is just a error. If you plan to own (or already own) any other Viltrox lens, do not download their mobile app to update your lens firmware. Viltrox tries to push users to download their app but it’s basically abandoned and only lists 2-3 lenses. Whether you’re on a Mac or PC, you can still download the firmware through your computer on their website.
The optical design uses 12 elements in 10 groups, with 9 diaphragm blades. For this price it is impressive they fit in this many elements to help with image quality. 12+ diaphragm blades usually help with achieving more circular bokeh balls, but it is not a deal breaker for a budget lens like this. The front filter diameter is 52mm, which isn’t uncommon, but top-end filter manufacturers typically don’t produce this diameter as often as their larger sizes (ex. 67, 77, or 82).
Performance
If you removed the Viltrox branding, I would have easily thought this was a native Sony G lens for APS-C cameras. It really performs that well.
The autofocus is hands down the fastest I have ever used on a budget third-party lens. It is snappy, quickly locking onto subjects without hesitation. Occasionally there is a very small moment of focus hunting when switching between two very different focus planes, but you would need to replay the footage in slow motion to even notice.
Sharpness in the center is tack sharp wide open at f/1.7 and stays consistent across the aperture range. The edges of the frame show some vignetting and slight chromatic aberration, but it is all well within acceptable levels. There is no built-in Lightroom lens profile for this lens yet, but manual corrections are easy enough if you need to clean up any distortion or vignetting.
Viltrox lenses often have a slightly warm color cast, probably due to their lens coatings, and that is true for this lens as well.
MTF Chart
I compared the Viltrox 25mm f/1.7 AIR directly against my Sony 24mm f/1.4 GM, which is easily my favorite and most-used lens for landscapes, astrophotography, video, and everyday street photography. The Sony 24 GM has such a strong reputation that, unlike a lot of other G Master lenses, it still hasn’t needed a second version. It just nails everything so well that Sony never had a reason to update it. It’s not exactly the most fair comparison but I think it’ll be interesting for people to view a similar focal length lens (when shot in crop mode) and see how well a sub-$200 lens stacks up against a $1300 native lens.
All tests were started with the Sony 24 GM at f/1.8 and the Viltrox wide open at f/1.7.
Autofocus:
In terms of still photography, the Viltrox and Sony have good AF performance. Both lenses will lock onto subjects, however, the Viltrox exhibits a half-second focus-hunting adjustment that might be hard to catch in real-time. I’ve slowed it down in a GIF below to exhibit the very quick double-focus adjustment the Viltrox is forced to perform while the Sony 24 GM nails focus without having to adjust.
When it comes to video too, the Sony has a slight edge. On my A7CR, tapping the screen to shift focus points feels just a bit faster and more confident with the Sony compared to the Viltrox.
Tap-To-Focus AF Comparison
Focus Hunting Comparison (Zoomed 500% and Slowed 50%)
Notice the Viltrox taking a small adjustment before locking in focus. It’s very quick and hard to notice in real-time, but when slowed down (dramatically) you can spot the focus hunting. I still think this lens has surprisingly responsive AF and I never found myself thinking this focus adjustment was an issue when using in the real world. I still think this is really impressive AF performance for a budget lens.
Sharpness:
Here is where it gets interesting!
In the center and mid-frame areas, the Viltrox is actually slightly sharper than the Sony, especially wide open. That really caught me off guard. That said, the Sony still wins out when you look at the edges of the frame. It maintains better sharpness across all apertures, whereas the Viltrox does not really clean up the edges until you stop down to around f/8 or f/11. Both lenses show some chromatic aberration around the corners, but again, the Sony handles it better with less vignetting and less color fringing once you start stopping down.
There’s also an obvious color cast on the Viltrox which skews toward a warmer image, while the Sony remains very neutral with a better white balance.
Sony 24 GM @ f/1.8 vs. Viltrox 25 AIR @ f/1.7
Sony 24 GM @ f/1.8 vs. Viltrox 25 AIR @ f/1.7
CENTER
Sony 24 GM @ f/1.8 vs. Viltrox 25 AIR @ f/1.7
CORNER
Bokeh:
When it comes to background blur, you can definitely tell the difference between the two. The Viltrox produces smaller bokeh balls and out-of-focus areas that look a little busy or nervous, especially with cluttered backgrounds, but honestly, that is expected for a sub $200 crop sensor lens. The Sony, on the other hand, delivers much bigger, softer, and more painterly bokeh, especially at f/1.4 and f/1.8. The Viltrox also exhibits some cats-eye bokeh once you go further from the center of the frame. If smooth, dreamy out of focus areas matter to you, the Sony is definitely in a different league. Out-of-focus rendering is definitely one of the Viltrox’s weaker spots.
But I want to clarify that this portion of the test is unfair to the Viltrox 25 AIR since it’s an APS-C lens with a smaller image circle while the Sony 24 GM is a full-frame lens with very large optical elements. No crop sensor lens is going to compete against a premium full-frame lens wide-open.
Sony 24 GM @ f/1.8 vs. Viltrox 25 AIR @ f/1.7
Flaring:
Still needs more testing. I want to shoot directly into some harsher light sources before making any final calls. I will update this section once I get more real-world samples.
Sample Images
Click on the photo to view a larger image.
Final Thoughts
Overall, this lens was a huge surprise. In real-world use, it felt just like a native Sony APS-C lens. Sure, if you pixel peep the edges, the Viltrox can’t match premium lenses, but out in the field, nobody would ever guess your photo came from a plastic $176 lens.
I used this lens for street photography in San Francisco and New York City, as well as at a corporate event, and it never missed a beat. Autofocus was quick, reliable, and paired perfectly with the compact Sony A7CR. Even though the Sony 24mm f/1.4 GM is considered compact for a full-frame lens, it still feels huge compared to the tidy, lightweight design of the Viltrox.
Pros:
Incredibly affordable price
Very fast and reliable autofocus
Excellent sharpness in the center wide open
Lightweight and travel-friendly design
Performs like a native Sony APS-C lens
Cons:
Noticeable edge softness and color fringing until stopped down
Busy and small bokeh rendering
No weather sealing
Cheap and fidgety lens hood
Rating: 4/5
If you are a Fuji or Nikon shooter, you should be excited about Viltrox introducing such competitive lenses at this price point. For Sony users, the arrival of the AIR series feels like a breath of fresh air, especially considering how much Sony has neglected its APS-C camera and lens lineup.
Third-party companies like Viltrox are stepping in and filling the gap that Sony and Zeiss left behind when they moved away from offering more budget-friendly lens options.
If you need an affordable, high-performing crop sensor lens, I would not hesitate to pick up the Viltrox 25mm f/1.7 AIR.