Tamron 20mm f/2.8 Di III OSD M1:2 review

I needed a major change in my life — moving to Guadeloupe — to finally start my first official lens review. Those of you who follow us on the blog already know that I’m passionate about photo gear, and I’ve already had the chance to test several accessories, especially camera lens filters. Testing lenses myself is something I’ve wanted to do for a long time. So here is my first lens review, dedicated to the Tamron 20mm f/2.8 Di III OSD M1:2, a wide-angle lens designed for the Sony E mount. I want to make it clear that this is not an advanced lab test with charts and measurements — you can already find several very good reviews of that kind. This is more of a real-world field review. I also want to mention right from the start that this is not a partnership with Tamron: I bought this lens myself when I switched from a Canon DSLR to a Sony mirrorless camera in 2021. My opinions and comments are entirely my own, and I remain fully in control of everything mentioned in this article.

If you want to know more, we’ve also written a full review of the Tamron 24mm f/2.8 FE.

This lens offers a 94° angle of view, which is perfect for wide shots, and sits more in the entry-level to mid-range category. Its main competitor — although they do not really play in the same league — is the Sony FE 20mm f/1.8 G, which costs roughly three times more at around €1000.

A few words about why I made this choice. I love landscape photography, and when I was shooting with a DSLR, I bought the excellent Canon 16-35mm f/4 L IS. But when I switched to a mirrorless camera, I had to make a choice. Considering my budget and the way I mainly shoot landscapes, either during the day or in low light on a tripod, I was left with three realistic options: the Tamron 17-28mm f/2.8 Di III RXD, which was my initial choice, and two prime lenses, the Sony 20mm f/1.8 G and the Tamron 20mm I’m reviewing here. After a lot of thought and some help from Alex (he’ll recognize himself, and I know he reads the blog), I finally chose the Tamron 20mm. I didn’t need the wider f/1.8 aperture of the Sony, and I preferred to save money rather than buy the Tamron 17-28mm, even though it has an excellent reputation and is considered one of the best wide-angle zooms for Sony. Some reviewers, such as Dustin Abbott, even say that if you already own the 17-28mm, there is little point in buying the 20mm unless you use a very high-resolution sensor. By the way, we have also published our full review of the Tamron 17-28mm f/2.8!

In any case, I hope this type of article helps you better understand camera lenses and choose the right one for your own needs.

Let’s start with the basics. What do you actually get with this Tamron 20mm lens? First, here are its main features:

In terms of focal length, a 20mm lens sits somewhere between ultra-wide-angle lenses with shorter focal lengths — such as the Sony 16-35mm, 12-24mm, or even the Samyang AF 14mm — and the more classic 24mm focal length. Personally, I think 20mm works particularly well for landscape photography, architecture, and even some reportage work, especially because this lens lets you get very close to your subject. And although it is designed for a full-frame sensor, it can also be used on a Sony APS-C body, where it gives an equivalent focal length of about 30mm.

As for the f/2.8 maximum aperture, I think Tamron made a sensible choice. This lens does not compete directly with the Sony 20mm G, which is positioned higher up the range with its f/1.8 aperture. For landscape photographers, who often shoot at smaller apertures such as f/5.6 to f/11, f/2.8 is more than enough. At full aperture, the lens can still be used in low light, especially when combined with the in-body stabilization of Sony cameras, which allows you to use fairly slow shutter speeds below 1/10 sec.

By limiting the aperture to f/2.8, Tamron also managed to keep the lens very compact. It measures only 6.4 cm long and 7.3 cm wide, with a total weight of 220 g. It can easily fit into a shorts or jacket pocket, although I wouldn’t necessarily recommend carrying it that way, haha. The Sony, by comparison, is almost twice as heavy and less compact, which makes sense given its wider maximum aperture. The Tamron also offers a 1:2 magnification ratio, marketed as “macro” by Tamron, which makes it genuinely interesting for close-up and proxy photography. Its very short 11 cm minimum focusing distance lets you get extremely close to your subject and create pleasing background or foreground blur, even at 20mm. Because you can focus at 11 cm, compared with 19 cm on the Sony, you can achieve background blur that is just as attractive as with the Sony. The depth of field is even shallower at f/2.8 with the Tamron at 11 cm than with the Sony at 19 cm and f/1.8.

Tamron’s optical construction uses 10 elements in 9 groups. Aspherical and LD elements help reduce chromatic aberrations, while Tamron’s BBAR (Broad-Band Anti-Reflection) coating helps limit flare. The lens uses an OSD (“Optimized Silent Drive”) autofocus motor, which is not as fast as the RXD motor found on the 17-28mm or 28-75mm, and even less responsive than the VXD motor used in the 70-180mm that I will review soon (I bought that one too). Personally, for landscape photography, this does not bother me. Finally, the lens is not stabilized, but it does have an all-weather construction that is resistant to splashes and dust. There is a seal around the lens mount and several internal seals. The front element also has a fluoride coating, which makes cleaning easier, and the filter diameter is 67mm. The lens comes with a hood.

I have to admit that switching from Canon’s high-end lenses, such as my Canon 16-35mm L IS, to this Tamron felt a little strange at first. The build quality is good without feeling exceptional, but we are talking about a lens that costs “only” around €400. It is mainly made of plastic, with a metal mount. The overall look is black, satin-like, and pleasant to the touch. The name of the lens and the brand are printed in white on the barrel. There is no button, not even an AF/MF switch, which I would have liked, so you have to go through the camera menu for manual focus. There is a silver-gold ring at the base of the lens, as well as a mounting mark. The focus ring is about 2 cm wide and feels good to me, with a fairly smooth rotation. There is no aperture ring either, which is a shame for video. One small detail: I found the lens quite stiff to mount and remove from my A7III at first, although it improved later.

If you look at the front of the lens, you can see that the front element is slightly bulbous. When focusing, the internal unit moves slightly, but it stays inside the barrel. The lens does not extend while focusing, so you can use standard screw-in filters without any issue. Tamron has also chosen a classic 67mm filter diameter for most of its lenses, except for the Tamron 150-500mm f/5-6.7 Di III VC VXD, which uses 82mm filters. This means you can use the same type of filter, such as an ND or polarizing filter, across several Tamron lenses if you own them. Finally, the lens comes with a simple plastic petal hood that does the job quite well. Mounted on my A7III, the setup feels well balanced and fairly light, at around 800 g. It is discreet and easy to carry. Compared with my 6D + 16-35mm setup, this combination feels much lighter and more discreet — because it really is. The first few times, I almost felt like I had nothing in my hands.

In the end, I find the design and build quality of the lens quite good. This is clearly not a high-end lens in terms of construction, but given the price, I think Tamron offers a very solid package.

The lens uses an OSD (“Optimized Silent Drive”) motor, which is not as good as the RXD and VXD motors mentioned above. In my opinion, this is where this little Tamron starts to show its limits. But again, it is all about compromise. I mainly use it for landscapes, so autofocus speed is not a major concern for me. It could be more annoying for reportage work or portraits, where the AF may not be fast enough to catch a subject passing close to you, for example.

Generally speaking, with still subjects, I would say the AF performs well enough without being especially fast. I also noticed a bit of AF “pumping” on still subjects. But for landscapes in AF-S mode, it is perfectly fine. In AF-C mode, results are better, although I still would not call them excellent. To be fair, AF-C is not very useful for landscape photography. It becomes more relevant for reportage or portraits, for example when you want to quickly capture a subject in motion. In that kind of situation, things are not always easy with an autofocus system that can sometimes feel a little slow. That said, I did some proxy photography tests on flowers and moving branches in AF-C mode, and it kept up quite well in my opinion. For my use, that works fine, even if the AF is not really quiet.

I also tested the lens quite a bit in low light, at night or very late in the evening, and the autofocus did struggle to lock on sometimes, with occasional pumping. Again, for landscapes, this is not a major issue, and you can always focus manually.

I won’t go into detail about autofocus for video, simply because I do not use it much. From the tests I have done, it is also quite noisy, and many users mention that the focusing noise can be heard while recording. As a reminder, there is no aperture ring on this lens. I also found that the AF always lagged slightly behind as soon as I changed framing or subject distance. Clearly, if video matters to you, I would recommend going for the Sony instead. It is much more interesting in that regard, with fewer optical flaws, a click/de-click aperture ring, and better AF.

Manual focus works quite well too, even if I sometimes find the ring a little stiff. When focusing manually, you can display the focus distance on the screen or in the EVF, as well as the area in focus using focus peaking. This helps you check the precise focus area in your image. The focus peaking display can be adjusted in the Sony menus, especially in terms of sensitivity and color.

Finally, human eye tracking also works pretty well, although I doubt many people will use this 20mm for portraits. From the few tests I was able to do, for example while photographing my sons at very close range, the eye was not always tracked perfectly. Again, this is a 20mm lens, so it is not designed primarily for portraits. You have to be very close to your subject and pay attention to distortion. However, when your subject is farther away and Eye AF does not work, face detection still helps. With a 20mm lens, even at f/2.8, the depth of field is usually enough to keep the whole subject sharp.

When it comes to optical flaws, this is where the lens struggles a bit. Barrel distortion is very pronounced. Clearly, for architecture photography, I would rather use another lens. However, in-camera correction on JPEGs fixes most of the problem. If you shoot in RAW, you will need to use the lens correction profile in specialized software such as Lightroom or DxO. It works well, but you lose a little of the image when cropping. For those wondering, the Tamron 17-28mm has almost no distortion, and the same goes for the Sony 20mm G. Distortion becomes even more noticeable when you place a horizon close to the top or bottom edge of the frame.

Here is an example of very strong distortion on the garage of my house. You can clearly see that post-processing in DxO improves things considerably.

Here is another example, this time on a landscape photo where the distortion is less pronounced. You can still see that the horizon on the right looks more natural after correction.

Chromatic aberrations are well controlled, and I did not encounter any major issue. Vignetting, on the other hand, is very strong at full aperture (f/2.8), decreases at f/4, and almost disappears at f/5.6. Both vignetting and chromatic aberrations are easy to correct in post-processing software if you shoot in RAW. Finally, the lens offers excellent flare resistance.

Very strong vignetting at full aperture (f/2.8, left), but very easy to correct in post-processing with DxO (right).

As I mentioned at the beginning, I will not go into an extensive lab test, as I do not have the equipment for that and others have already done it very well. Overall, I am really satisfied with the image quality delivered by this little Tamron 20mm. The results I get in the field are consistent with the technical tests I have seen, whether in the lab or on test charts.

Image quality is already very good in the center at full aperture (f/2.8). The edges are a little behind, but I never shoot landscapes at f/2.8, so it does not really bother me. Sharpness improves slightly at f/4 and f/5.6, where it becomes excellent. I would say the ideal aperture for a sharp image from center to edge is f/5.6. Diffraction starts to appear from f/11 and reduces image quality on my A7III and its 24MP sensor when viewed at 100%.

Here is an example of a sharpness test on the pineapple photo shown above, in the center of the image. You can see that sharpness improves when stopping down to f/5.6, and this is even more noticeable on the edges of the frame.

For landscape or architecture photography, I find this lens very interesting and very good overall.

This is one of the reasons why I chose this 20mm prime lens instead of a wide-angle zoom: its macro possibilities. Of course, a short 20mm focal length will not separate the subject from the background as strongly as an 85mm or longer lens. However, this Tamron offers a 1:2 magnification ratio and a very short 11 cm minimum focusing distance, which makes it possible to create an extremely shallow depth of field and pleasing background bokeh.

I was genuinely surprised by the quality of the backgrounds you can create by getting as close as possible to a flower or a detail in the vegetation. If the background is far enough away, you can get soft, pleasant bokeh with a lovely transition between the sharp and blurred areas. The bokeh balls are round at full aperture in the center of the image, with the usual cat’s-eye shape toward the edges, as on most lenses. But as soon as you stop down, the bokeh balls start to take on a heptagonal shape, which comes from the 7 diaphragm blades.

By using manual focus and focus peaking, you can place the focus exactly where you want it. Image quality remains very good, even at this short focusing distance. In my opinion, this is a very interesting point to consider if you enjoy proxy photography, especially compared with the Sony, which costs about three times more.

I’m coming to the end of this first review, and I wanted to talk about the alternatives to this Tamron 20mm. There are several options depending on your budget and the type of photography you do. In a few words, here is what I would say:

• I won’t go into detail about Sony zoom lenses that include the 20mm focal length, such as the Sony 16-35mm f/2.8 GM, the Sony 16-35mm f/4 ZA Vario-Sonnar T* OSS, the Sony 12-24mm f/4 G, or the Sony 12-24mm f/2.8 GM. Newer compact zooms such as the Sony FE 16-25mm f/2.8 G or the Tamron 20-40mm f/2.8 Di III VXD are also worth considering if you want more flexibility. All these lenses are more versatile than a prime lens, but their price, size, and purpose are not really in direct competition with this small Tamron 20mm.
• I hesitated for a long time with the Tamron 17-28mm f/2.8 Di III RXD, which offers excellent image quality and needs no introduction. It is heavier, although still light for this type of zoom, less compact, and roughly twice as expensive as this much-praised Tamron 20mm. Tests also show slightly better overall image quality from the 20mm compared with the 17-28mm at 20mm, although the difference is not huge.

• As for prime lenses, as I said earlier, comparing this Tamron to the Sony 20mm does not seem very relevant to me. They are not in the same range or at the same price. The same goes for the Zeiss Batis 18mm f/2.8, which offers good image quality but comes at a very high price.
• There is now a much more relevant Sigma option than the older adapted DSLR lens: the Sigma 20mm f/1.4 DG DN Art, designed directly for mirrorless cameras. It is a serious choice for astrophotography or anyone who needs a very bright 20mm, but it is still much larger, heavier, and more expensive than the Tamron. The older Sigma 20mm f/1.4 DG HSM Art exists too, but it is a DSLR lens adapted to mirrorless, so it is no longer the version I would prioritize.
• Another interesting option is the Sigma 20mm f/2 DG DN Contemporary, which is compact, well built, and brighter than the Tamron. It is more expensive, though, and it does not offer the same 1:2 close-up capability. At the other end of the budget range, the Viltrox AF 20mm f/2.8 FE has also become an attractive low-cost alternative, but I would still give the Tamron the edge if proxy photography and all-weather construction matter to you.
• Except for manual focus lenses such as the Voigtländer 21mm f/1.4, Zeiss Loxia 21mm f/2.8, or Viltrox 20mm f/1.8, the closest budget competitor remains the Samyang 18mm f/2.8. In my opinion, the Samyang is still less interesting overall. It is not weather-sealed, image quality is better on the Tamron, and it does not offer the same ability to get very close to the subject for macro-style photography.

Here is a short table summarizing its main advantages and disadvantages.

I’m coming to the end of this review of the Tamron 20mm, a lens I bought myself and genuinely enjoy using. In my opinion, Tamron has done a very good job here, offering a lens with solid image quality, compact size, weather-resistant construction, and a very attractive price of around €350. This lens does not really compete with everything already on the market, and I would happily recommend it to anyone looking for a wide-angle lens for landscapes, architecture, and even some reportage work. For the price, it is hard to be disappointed, even if the lens is obviously not perfect, with autofocus that could be better, very strong distortion, and lower sharpness on the edges at full aperture.

In the end, this Tamron lens feels balanced, versatile, and excellent value for money for photographers who want to shoot landscapes, architecture, and even some reportage. If you want to go further, feel free to check out our article on the best Sony wide-angle lenses.

Finally, you should know that if you use the links in this article to order your lens, we earn a small commission at no extra cost to you. It’s a simple and helpful way to support our blog if you enjoyed this lens review. See you soon for a new review, probably my Samyang 35mm AF f/1.8.

In the meantime, thanks to Alex, we have also reviewed the Sony FE 20mm f/1.8 G, a high-end 20mm lens that is perfect for photographers looking for top image quality and a wider maximum aperture.

Written by Sylvain PONS

I've been passionate about photography since 2010, learning as I went along. Today, I dedicate myself to guiding others in their choice of camera gear and sharing a variety of tips to improve their photography skills.

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