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

I needed a new change in my life (moving to Guadeloupe) to finally start my first official lens review. Those of you following us on our blog already know that I’m a photo equipment enthusiast, and I’ve already had the opportunity to test several accessories, especially camera lens filters. Being able to test lenses on my side is something I’ve always wanted to do. Here is then my first article with the review of the Tamron 20mm F/2,8 Di III OSD M1:2, a wide-angle lens adapted for the Sony E mount. I would like to clarify that this will not be an advanced test on test charts or in a Lab (you will already find several reviews very well done), but rather a real test in the field, I would say. I also specify right from the beginning that this is not a partnership with Tamron, and I did fully pay my lens when I switched from Canon DSLR to Sony mirrorless, in this year 2021. My opinions and comments are my own, and I remain entirely in control of everything that can be mentioned in the article.

This lens, offering a 94° angle of view (perfect for wide shots), is more of an entry-level (or mid-range) lens. Its only competition, which is not really, is the Sony FE 20mm F/1.8 G – although they don’t really play in the same league, as it is three times more expensive (about 1000€).

A few words about why I made this choice. I am a landscape photography enthusiast, and when I was using a DSLR, I bought the very good Canon 16-35mm f/4 L IS. But then it was time to change for a mirrorless camera, and I had to make a choice. Considering my budget and my use mainly in landscape (daytime or in low light on a tripod), I was finally limited to three choices I could have considered: the Tamron 17-28mm f/2.8 Di III RXD (my initial choice), and two fixed focal lengths, the Sony 20mm f/1.8 G and the Tamron 20mm (the one I’m reviewing today). After a lot of considerations and help from Alex (he’ll recognize himself, I know he reads around here), I finally decided to go with the Tamron 20mm. I won’t need the wide f/1.8 aperture of the Sony, and I preferred to save money by not buying the Tamron 17-28mm which has yet the excellent reputation of being one of the best wide-angle zooms for Sony. In fact, some reviewers like Dustin Abbott say that if you already have the 17-28mm, there is little point in getting the 20mm, unless you have a very pixelated sensor.

In any case, I hope that this kind of article will help you to better understand camera lenses and choose yours.

Let’s start with the basics. What will you find on this Tamron 20mm lens? First, here are the main features of this lens:

Regarding focal length, we must admit that a 20mm lens falls in the middle between ultra-wide-angle lenses offering shorter focal lengths (I’m thinking for example of the Sony 16-35mm or 12-24mm, or even the 14mm Samyang AF) and the more classic 24mm focal length. Personally, I think the 20mm is particularly suitable for landscape or architecture photography, or even for reportage. Especially since with this lens, you need to/could get really close to your subject. Note that even if the lens is dedicated to a full frame sensor, it can be used on a Sony APS-C body, giving an equivalent focal length of about 30mm.

About the f/2.8 maximum aperture, I think Tamron aimed accurately. It does not compete directly with the Sony 20mm G, which is rather intended for high-end with its f/1.8 aperture. The f/2.8 aperture is more than enough for landscape photographers who will tend to shoot at smaller apertures, from f/5.6 to f/11. However, at full aperture, this lens allows you to shoot in low light conditions if we consider, in addition, the sensor stabilization of Sony cameras, allowing you to use fairly low shutter speeds (below 1/10′).

Moreover, by limiting itself to an aperture of f/2.8, Tamron has managed to build a very compact lens. It is indeed only 6.4 cm long and 7.3 cm wide, for a total weight of 220g. It can clearly fit in the pocket of a pair of shorts or a coat (although I don’t recommend it, haha). Conversely, the Sony weighs almost twice as much and is less compact (which is normal considering its max aperture). Besides, the lens has a magnification ratio of 1:2, labelled as “macro” by Tamron, claiming its value in proxy photography. The short focusing distance of 11mm allows you to get very close to the subject as well as to get nice background (or foreground) blurs, even at 20mm. The fact that you can get closer at 11cm compared to the 19cm on the Sony will allow you to get as nice bokeh in the background as you’d have with the Sony. The depth of field will even be shorter at f/2.8 with the Tamron at 11cm, compared to the Sony at 19cm and f/1.8.

Tamron’s optical construction offers a set of 10 elements divided into 9 groups. Aspherical and LD lenses ensure a reduction of chromatic aberrations. Tamron also applies a BBAR (Broad-Band Anti-Reflection) coating, allowing to limit the flare. The lens offers an OSD (“Optimized Silent Drive”) autofocus, which is however not as fast as the RXD type found on the 17-28mm or the 28-75mm, and even less than the VXD present on the 70-180mm I will soon review (I also bought it). Personally, for landscape, it does not bother me. Finally, the lens, not stabilized, has an all-weather construction that is splash and dust resistant. It has a seal at the lens barrel, and several internal seals. Worth noting the fluoride coating on the front lens for easy cleaning (67mm diameter). The lens is supplied with its lens hood.

I have to admit that switching from Canon’s high-end lenses, like my Canon 16-35mm L IS, to this Tamron made me feel a bit weird at first. The construction quality seems correct without being exceptional. We are here talking about a lens which costs “only” 400€. It is essentially built in plastic on a metal mount. The general aspect of the lens is black, satin, very pleasant to the touch. Several elements such as the name of the lens and the brand are mentioned on the barrel in white letters. There is no button, not even an AF / MF button that we would have liked (so you will have to go through the camera for manual focus). We find a silver gold border at the base of the lens, and a mark to fit the lens in the camera. The focus ring, about 2cm wide, appears good to my eyes, quite fluid. Note that there is no aperture ring (too bad for the video). Another small precision: I find that this lens is rather hard to insert and remove on my body (A7III). It improved after though.

If you look at the front of the lens, you can see its slightly bulbous lens. When focusing, you can see the whole thing slightly moving, while remaining inside. The lens does not expand when focusing. You can then place conventional screw-in filters without any concern. Note that Tamron has decided to use a classic 67mm diameter on all these lenses, except for the Tamron 150-500mm f/5-6.7 Di III VC VXD (82mm). This allows you to use a classic filter (ND or polarizing type) on several Tamron lenses, if you have them. Finally, the lens comes with a simple plastic lens hood (petals) that does the job quite well. Mounted on my A7III, the package appears well balanced and rather light (about 800g). This makes it a discreet set to carry. Compared to my 6D + 16-35mm, this set seems to be really (actually, it is) lighter and more discreet. The first few times, I even felt like I had nothing in hands…

In the end, I find the design and quality of the lens quite good. We are clearly not on a high-end lens quality construction, but for the price given, I think Tamron offers a very good package.

The lens has an OSD (“Optimized Silent Drive”) engine that is not as good as the RXD and VXD mentioned above. In my opinion, this is a point where this little Tamron reveals its limits. Well, it’s all about compromise! I use it mainly for landscape, so I almost don’t care about the autofocus speed. But it could be more annoying for reportages or portraits, where the AF would not be fast enough to capture the subject passing close to you, for example.

Generally speaking, on still subjects, I’d say the AF does well without being incredibly fast (I’ve seen the AF “pumping” quite a bit on still subjects, too). But for still subjects like landscape, in AF-S mode, it’s actually fine. When shooting in AF-C mode, results are much better, though I can’t say they’re great either. But for its defense, for landscape, the AF-C mode is useless. It will only be useful for reportage/portrait, for example when you want to quickly catch a subject in passing. Indeed, in this case, it will not be so simple with an AF which is sometimes not very reactive. However, I did some tests in proxy photography on flowers or moving branches in AF-C mode, and it keeps up quite well in my opinion. This suits me for my use anyway, even if the AF is not really quiet.

I also did a lot of tests when the amount of light was not sufficient (night or very late evening), and the autofocus also has a hard time catching the subject and will also sometimes tend to pump. Again, on a landscape, this is not a real problem, and you can still focus manually.

I won’t talk about the AF in videos in detail, simply because I don’t use it much. But from the tests I’ve done, it’s also quite noisy, and a lot of users talk about a noise that can be heard when recording. I remind you there is no aperture ring on this lens. I personally found the AF always a little late, as soon as you change plans for example. Clearly, for people interested in video, I really advise to switch to the Sony, which is much more interesting (less optical defects, clickable ring, and better AF).

In manual focus, it works pretty well too, even if I find the ring sometimes a bit hard. During manual focusing, you can see a focus distance to the subject (on the screen or in the EVF), as well as the area on which the focus is done (focus peaking or intensification option). This allows you to be sure of the precise area of focus of your picture. It is adjustable and can be modified through Sony menus (sensitivity and color, in particular).

Finally, the human eye tracking works pretty well too (Eye AF), although I doubt that many people use this 20mm for portraits. From the few tests I’ve been able to do, for example when I try to shoot my sons at very close range, the eye is not always well tracked. Again, this is a 20mm, so not a lens aimed to shoot portraits. You will have to be very close to the subject and be careful of distortions. However, when your subject is far away and the eye-AF does not work, there is still the face detection which, with a 20mm, and even at f/2.8, will be enough to cover the whole subject given the depth of field.

Regarding optical defects, this is where the lens struggles a bit. We notice a very pronounced barrel distortion. Clearly, for architectural photography, I would rather use another lens. However, the correction of the camera on JPEGs fixes most of the problem. If you shoot in RAW, you will have to use the lens profile correction in a specialized software, like Lightroom or DXO. This works well, but you’ll lose some image when cropping. For those wondering, the Tamron 17-28mm has almost no distortion, same goes for the Sony G 20mm. Image distortion is even more pronounced when you place for example a horizon close to an edge (top or bottom).

Here is an example of a very strong distortion on the garage of my house. We can clearly see that post processing on DXO considerably improves things

And here is another example on a landscape picture, this time less pronounced. We notice however that the horizon on the right appears more correct.

Chromatic aberrations are well managed, and I did not encounter any major problem. Concerning vignetting, it is very strong at full aperture (f/2.8), reduces at f/4, and almost disappears at f/5.6. These two points are perfectly controlled anyway in post-processing software, for those who shoot in RAW. Finally, the lens offers a remarkable flare resistance.

Very strong vignetting at full aperture (f/2.8 – left) but very easy to correct in post processing (on DXO – right)

As mentioned at the beginning, I will not go into an extensive lab test, not having the equipment to do so, and knowing that others have done it before. Overall, I am really satisfied with the image quality offered by this little Tamron 20mm. I find myself in the technical tests results, either in laboratory or on test charts.

The image quality is already very good in the center and at full aperture (f/2.8). The edges are a bit behind, but I never shoot at f/2.8 for landscape, so it doesn’t really bother me. It slightly improves at f/4-5.6 to become excellent. I would say that the ideal aperture for a sharp image (from the center to the edges) would be at f/5.6. Diffraction appears as soon as f/11 and degrades the image quality on an A7III and its 24MP viewed at 100%.

Here is an example of a sharpness test on the pineapple picture shown above (in the center of the image). We can see that the sharpness improves by closing to f/5.6. It is even more true on the edges of the image

For landscape or architecture, I find the lens very interesting and of very good quality.

This is one of the reasons why I decided to buy this 20mm prime lens rather than a wide-angle zoom: its macro possibilities. Obviously, a 20mm short focal length does not allow to separate the subject from its background as much as you can with an 85mm or longer focal lengths. However, this Tamron offers a magnification ratio of 1:2 and a very short focusing distance of 11cm, allowing an extremely short depth of field and thus offering nice bokeh possibilities in the background.

I was myself amazed at the quality of the backgrounds (bokeh) that can be created by getting as close as possible to a flower or any detail in the vegetation. If you make sure the background is far enough away, you’ll get a nice bokeh, very soft, and with a beautiful transition between the sharp and blurred area. The bokeh balls are round at full aperture in the center (cat’s eye shape on the edges, as on most lenses), but you can see, as soon as you close the aperture, the bokeh balls turning into a heptagon, which corresponds to the 7 diaphragm blades.

By using manual focus and focus peaking, you can place the focus exactly where you want it. The image quality remains very good, even at this focusing distance. In my opinion, this is a very interesting point to consider if you are into proxy photography (compared to the Sony for example, which costs 3 times more anyway).

I’m coming to the end of this first review, and I wanted to talk about the alternatives to this 20mm from Tamron. There are different possibilities, depending on your budget and your photographic practice. In a few words, here is what I would say:

• I won’t talk in detail about Sony lenses offering this 20mm focal length, like the Sony 16-35mm f/2.8 GM zooms, the Sony 16-35mm f/4 ZA Vario-Sonnar T* OSS, the Sony 12-24mm f/4 G or finally the Sony 12-24mm f/2.8 GM. All these lenses have the advantage of being more versatile than a prime lens, but their price and range are not in direct competition with this small 20mm Tamron,
• I hesitated for a long time with the Tamron 17-28mm f/2,8 Di III RXD, which offers an excellent image quality and needs no introduction. However, the lens is heavier (but still light for this kind of zoom), less compact and twice as expensive as our much-vaunted Tamron 20mm. Tests also show overall better image quality on the 20mm compared to the 17-28mm at 20mm, although the difference is not huge,

• About prime lenses, as I said in the article, comparing this Tamron to the Sony 20mm doesn’t seem very interesting. Again, it is not the same range nor the same price! The same goes for the Zeiss Batis 18mm f/2.8 which offers good image quality but at an extremely high price,
• You will also find the Sigma 20mm F/1.4 DG HSM Art, which has a very good reputation but is a lens built for DSLRs and adapted for mirrorless. It will cost you 1000€ and weigh 1kg…
• Except for manual focus lenses (e.g., Voigtländer 21mm F1.4, Zeiss Loxia 21mm F2.8, Viltrox 20mm F1.8), the only real competing lens in my opinion is the Samyang 18mm f/2.8. To my mind, the Samyang, while priced almost identically, is still inferior. It does not have an all-weather build, the image quality is better with the Tamron, and it does not have the ability to get close to the subject (macro photography).

Here is a small table that summarizes its advantages and disadvantages.

I’m coming to the end of this little Tamron 20mm that I bought and I truly enjoy using. In my opinion, Tamron succeeded by offering a great quality lens, a good image quality, a reduced compactness, an all-weather construction, all for a very attractive price (350€). This lens doesn’t really compete with what’s already out there, and I really recommend it to anyone looking for a wide-angle lens to shoot landscapes, architecture, or reportage, to some extent. For the price, it’s hard to be disappointed, even if the lens is obviously not perfect (AF can be improved, very important distortion, lower sharpness on the edges at full aperture).

In the end, the lens proposed by Tamron seems to me balanced, versatile and an excellent value for money for photographers wishing to shoot landscapes, architecture and even reportage. For those who want to go further, feel free to check out our article on the best Sony wide-angle lenses.

Finally, you should know that by using the links in our article to order your lens, we earn a small commission without the price changing for you, of course. It’s a simple and nice way to support our blog if you liked the review of this lens. See you soon for a new review, probably my Samyang 35mm AF f/1.8.

In the meantime, we also reviewed, thanks to Alex, the Sony FE 20 mm f/1.8 G, a high-end 20mm, perfect for people looking for a high-quality lens with a large aperture.

Sylvain