Viltrox AF 13mm F1.4 STM Review
May 23rd, 2022
Viltrox has proven to be an aggressive new player on the lens market that isn’t afraid to take some risks. I started reviewing manual focus lenses from them, which quickly turned to autofocus lenses. They’ve boldly gone into new market space – Fuji X, Canon M, Canon RF, Nikon Z, along with the Sony platform they started on. What’s interesting is that three of those platforms (Canon RF, Fuji X, and Nikon Z) have been mostly closed platforms with little apparent interest in third party development (though that is changing over at Fuji). The newest lens from Viltrox is the Viltrox AF 13mm F1.4 STM (we’ll call it the Viltrox AF13 for brevity in this review) which joins the 85mm F1.8 STM as one of their very best to date.
Why? Because it builds on the formula they’ve had to date but improves some key areas of weakness that I’ve consistently seen over my many Viltrox reviews. The Viltrox AF13 has the most mature autofocus performance I’ve yet seen (and that is on Fuji, as the XF mount is the one that arrived to market first. I typically don’t find autofocus performance as good on Fuji as I do on Sony or Canon). They’ve done a great job of reducing distortion and chromatic aberrations relative to previous lenses. That’s particularly impressive when you consider that this is the widest lens that Viltrox has made to date and also when you consider how wide the maximum aperture is at this focal length (F1.4).
So how wide is this lens? Since it is designed for APS-C cameras, you have to apply the crop factor of the camera to the effective focal length. Fuji’s is called 1.5x (like Sony), but is actually a little larger than that, so we get a 20mm full frame equivalent rather than the 19.5mm we’ll see on Sony. Either way, this is a great focal length. It isn’t extreme but is rather in what I call the “sweet spot” for most landscape and architectural use. Interior spaces look wide but still natural in a way that wider focal lengths can lack.
You can see the low levels of distortion in the lines of the room. This will be a nice lens for those that want to do real estate video or photos.
It’s not a perfect lens, as we’ll see, and there are still a few of the familiar Viltrox weaknesses around, but I do think the new Viltrox AF13 is one of Viltrox’s best efforts to date. The MSRP as it comes to market is $430 USD (though if you buy it from the Viltrox store and use code DUSTINABBOTT you can get 10% any Viltrox product, including this lens) . For that money you are getting a nicely built, versatile lens, though it isn’t a perfect performance. We’ll break down the strengths and weaknesses in this review. If you prefer to watch your reviews, you can check out my definitive video review…or just keep reading.
Thanks to Viltrox for sending me an evaluation copy of the 13mm F1.4. As always, this is a completely independent review.
Viltrox AF13 Build and Handling
There aren’t really any surprises here in the build and design of the lens. Viltrox has consistently made lenses that feel like anything but “plastic fantastics”. There’s a high degree of metal in their build quality, and in the case of the Viltrox AF13, that includes a metal lens hood.
This is a great aesthetic match to Fuji lenses, and looks very much like some of their more premium designs. The Viltrox AF13 is larger than typical size for their APS-C lenses, with a broader diameter that looks more like their full frame lenses. You can see how it compares to their Fuji X-mount 33mm and 56mm F1.4 lenses:
It is 74mm in diameter (leaving a common 67mm front filter thread) and is 90mm in length. It weighs 420g. The 33mm (the 23mm, 33mm, and 56mm lenses are highly similar in size) is 65mm in diameter and 72mm in length, weighing only 270g. The Viltrox AF13 is in fact larger and heavier than the full frame 24mm F1.8 lens from Viltrox.
That’s not to say that this is an onerously large or heavy lens (it isn’t), but in some ways its size and bulk make it feel like a more premium lens. It has that feel, too, with all metal construction and a dark, sleek look that is a cut above most lenses at this price point.
What is unfortunately still missing is weather sealing. This is (at least) an internally focusing lens, so there is nothing that moves where dust might intrude. There is no gasket at the lens mount, though there is a USB-C port there that allows you to do firmware updates right to the lens.
I’m a fan of this approach, as it eliminates the need for a separate dock or lens station for firmware updates, and I find the process a little more intuitive than even doing firmware updates through the camera. This allows Viltrox to future proof their lenses and continue to improve them through firmware.
There is an aperture ring on the lens that behaves similar to many Fuji lenses. It is clicked (no de-click option) with 1/3rd stop detents and you can twist it fully to the left if you want automatic control of aperture within the lens.
There are no switches on the barrel, though that too is pretty common for Fuji primes.
The other ring is the wide zoom ring. It has ribbed, metal surface with nice grip and feel. This is a better experience than many lenses, with enough weight and feel to seem almost like a mechanical manual focus ring. Certainly a better experience than many mirrorless lenses.
There is no image stabilization, so I relied on the IBIS from the Fuji X-T4. Your mileage may vary depending on what camera body you’re using.
There are nine rounded aperture blades inside, and it seems like Viltrox is doing a better job of having properly centered aperture blades.
One lingering Viltrox weakness remains, and that is in minimum focus and maximum magnification performance. MFD is 22cm (8.7″) and the resulting magnification is only 0.10x:
Opportunities to get really close to things and blur out backgrounds will be limited with this lens.
Beyond those few weaknesses, however, this is a very nicely executed package. The lens feels high quality in the hands, and it handles quite nicely. It’s going to be a better match to the larger Fuji bodies than the compact ones (X200, etc…), but that’s a given. I would say the lens offers quite good “bang for the buck” in terms of quality.
Viltrox AF 13mm F1.4 STM Autofocus Performance
The STM motor on the Viltrox AF 13mm F1.4 was a winner, providing some of the best autofocus that I’ve experienced with ANY lens (including native Fuji lenses) on the Sony platform. Autofocus was fast, quiet, and smooth. I experienced the best focus pulls that I’ve ever seen on a Fuji camera, with fast, smooth focus pulls with no obvious stepping (typically a weakness for Fuji lenses). I could not pick up any sounds during focus with the onboard camera.
I also found that the transitions from my face to my hand during my tests were smooth and confident, with focus immediately returning to my eyes when the obstruction was removed. Focus breathing is also minimal, making this a nice lens for video or vlogging (due to the excellent focal length for this task).
In short, this was the best video autofocus performance that I’ve seen on a Viltrox lens.
I also had good performance for stills, with good eye detection and accurate focus even at closer focus distances and F1.4. You can see how well focused and sharp the image of Loki is above.
A little bit further away I was still able to get focus “nailed” with accurate focus on my subject.
Stepping back a little further, I had no problem “hitting the broad side of a barn” at F1.4:
In short, autofocus was excellent, and the addition of the USB-C port allows firmware updates to further improve focus results in the future.
Viltrox AF13 Image Quality
Viltrox has pulled out all the stops with this lens and has included a number of exotic elements in the optical construction, leaving an MTF results that looks quite good at F1.4 and great when stopped down to F8:
As noted earlier, there are a certain trends/traits that I associated with Viltrox lenses, and while some of these are improved here, there are a few lingering areas that I would like to see Viltrox improve upon. That being said – I think this lens (along with their surprisingly strong 85mm F1.8) is one of their best lenses to date.
One area where I do see clear improvement is in the area of LoCA (longitudinal chromatic aberrations). Viltrox lenses have frequently suffered from more fringing than what I would like (particularly green fringing after the plane of focus), but I find that the Viltrox AF13 is delivering a nicely neutral performance here. You can see next to no fringing either on the edge of the tulips (along with nice detail even at F1.4) and no fringing on the transition of the window frame to the bright outdoors.
That’s real progress.
I’m also satisfied with the control of LaCA (lateral chromatic aberrations) that typically show up along the edges of the frame with high contrast transition points (like the bare branches against the bright sky below).
There is little fringing to be seen here, which is another positive development.
If we move on to vignette and distortion we find even more positive developments. There is next to no distortion at all (I did no correction) and vignette is moderate, requiring a +54 to correct (right under two stops).
That makes this a good lens to consider for those who do real estate or interior photography, as lines are naturally nice and straight without correction, which also means that you retain a wider angle of view (nothing is lost in correction). This image (as shown before) gives you the full width of the native focal length without losing anything to correcting lines.
So far things are looking very positive. We’ll move on to inspecting our test chart. This test has been done on a 26MP Fuji X-T4 sensor, currently the highest resolution sensor that Fuji offers in the APS-C space. I use a high end tripod and two second camera delay to ensure vibration doesn’t affect images. Here’s a look at the test chart that we will examine at high magnification:
If we take a look at crops at F1.4 from the center, mid-frame, and lower right corner, we find that center and mid-frame performance is very good, but there is a steep drop-off in the corners (something I’ve frequently observed with Viltrox lenses).
You can see that steep drop-off in this comparison:
If you don’t look too closely at the corners, however, you will find that an F1.4 image doesn’t look much different on a global level than a stopped down image (first image in the series below is F1.4, second is F5.6, third is a crop from the center of those images).
Stopping the lens down will produce only minor improvements in the center and mid-frame, but you can see obvious improvements in the corners at F2.8:
At F5.6 and F8 (F5.6 shown below), you will find a much more even performance across the frame:
I went out in the very last light of day and was able to get very credible landscape images at apertures of F2 and F2.8, however:
Minimum aperture is F16, but you will see some effects of diffraction, so I would recommend staying at an aperture no smaller than F11 if possible.
I don’t find Viltrox color rendition top tier (processing needs a delicate touch to avoid colors going garish), so this is one area where I think native Fuji lenses have an advantage. That being said, I had plenty of images where I felt like the image as a whole (including the color) was very nice.
Here’s another where I felt like saturation levels were nice and intense but still natural.
Any lens with a wide angle of view and a large maximum aperture is going to be a potential candidate for astrophotography. The Viltrox AF13 is no different. I had a slightly difficult time nailing focus perfectly in the dark, but I did find that there is a bit of coma at F1.4 that seems to improve by F2, where the results were quite good (mostly some stretching of star points due to the length of the exposure).
This is a definitely a candidate for all kinds of night-time photography due to the great focal length and maximum aperture.
The low magnification levels of the Viltrox mean that there won’t be a ton of opportunities for high diffused backgrounds even with the F1.4 aperture. I found the bokeh quality where I could capture it to be only average – neither particularly bad or particularly good.
Flare resistance is really situational, in that there were certain images where I experienced a high level of flare and others where it was fairly well controlled. The worst performances seemed to be when the sun was near the edge of the frame, while the best results came with the sun a little further into the frame. Certainly not a flawless performance – I’ll let you judge for yourself from these images.
I’ll conclude this section by noting that my overall feelings about the Viltrox AF13 are very positive. I think this is one of their best lenses to date, and the list of optical strengths in my opinion far outweigh the list of optical flaws. You can check out more photos by visiting the image gallery here.
The Viltrox AF 13mm F1.4 is a very welcome addition to the Fuji catalog. It gives a high quality alternative to some Fuji options at roughly 50% of the price. It is a fairly sophisticated lens for such a new brand, with good build quality, excellent autofocus performance, and a strong optical showing. A lens with this wide of a focal length and this large of a maximum aperture isn’t easy to engineer, but Viltrox has pulled it off with a fair amount of aplomb here.
It’s not a flawless lens, proving a bit flare prone and with soft corners until F2.8, but those weaknesses are easily outweighed by an exceptional performance in distortion and chromatic aberration control. Yes, I would love to see Viltrox start to employ weather sealing into their designs, but it’s also reasonable to point out that many lenses in this price range also lack weather sealing.
At a price point of $429 USD, the Viltrox AF13 offers great value for money. Fuji shooters really have nothing quite like this lens, and I suspect the Viltrox will be interesting to many on that platform. And even when it inevitably moves on to mounts like Sony E or Canon M, I think there will still be a market for such a high performing lens that goes this wide. I can easily give my recommendation for this one!
- Nice build
- STM focus motor provides a smoother, quieter focus experience than most Fuji lenses
- Faster maximum aperture than some competing lenses
- Smooth, quiet, confident focus pulls in video
- Excellent center and midframe sharpness at wide apertures
- Good control of aberrations
- Very low distortion for a wide angle lens
- Fairly good coma control
- Good lens for interiors due to straight lines
- USB port for firmware updates
- Good price to performance ratio
- No weathersealing
- Corners soft at wide apertures
- Can be flare prone
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Keywords: Viltrox, Viltrox AF, Viltrox 13mm, Viltrox 13mm, F1.4, f/1.4, STM, Viltrox AF 13mm F1.4, Viltrox 13mm Review, Viltrox 13mm F1.4 Review, X-mount, Fuji, Fujifilm, Fujinon, Review, X-T4, X-S10, Bokeh, Portrait, X-T200, Dustin Abbott, Tracking, Hands On, Video Test, Sharpness, Autofocus, Build, Real World, Letthelightin
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