The Tamron 20mm f2.Eight Di III OSD M1:2 is an ultra-wide prime lens for Sony’s E-mount mirrorless cameras and corrected for full-frame use. It’s a part of a 3 lens collection from Tamron all of which have the distinguishing characteristic of a most magnification of 1:2. This let’s you get nearer to your topic and reproduce it at half life-size – albeit at a meager working distance of solely 3cm (1in.). This makes it the one 20mm lens with autofocus able to magnifications bigger than 1:3. In comparison with the Sony FE 20mm f1.Eight G the Tamron additionally has the advantage of being the smaller, lighter and considerably cheaper various, albeit one which’s greater than a cease optically slower.
Details from the catalog
As common I’ll take a look on the technical knowledge of the brand new Tamron 20mm f2.Eight M1:2 first. I’ve rated the options with a [+] (or [++]), when it’s higher than common and even cutting-edge, a  if it’s customary or simply common, and [-] if there’s an obstacle. For this comparability I exploit the Sony FE 20mm f1.Eight G (“Sony” for brief). Please remember the fact that the Sony has a 4/Three of a cease brighter focal ratio which influences dimension, weight, and worth of that lens.
Measurement (diameter x size): 73 x 64mm (2.9 x 2.5in.). The lens hood provides 19mm and is 87mm in diameter. The Sony is for much longer at 74 x 85mm + 22mm lens hood. [+]
Weight: 220g (Eight oz.) plus 21g for the lens hood. The Sony is 373g (13 oz.) + 17g lens hood. [+]
Optics: 10 components (together with one aspherical and three particular dispersion components) in 9 teams. The Sony is a extra elaborate design with 14 components in 12 teams, Nano-Coating to cut back flare, glare and ghosting, plus fluorine coating on the entrance to repel water, mud, and dust. 
Closest focus distance is 0.11m (4in.) with an excellent magnification of 1:2 however the working distance is a meager 3cm (1in.). A magnification of 1:10 is achieved at 0.25m giving a working distance of 15cm with lens hood connected. The Sony achieves a magnification of 1:3.Eight in guide focus at 0.17m (7in.). Working distance at minimal object distance is 7cm (3in.). [+]
Filter-thread: 67mm, similar because the Sony. [+]
Picture stabilization: The lens presents no optical stabilization. The Sony A7 Mark II our bodies onward present built-in sensor-shift stabilization. Identical with the opposite lenses on this comparability. 
Auto focus: Constructed-in AF drive. Handbook-focus override is by merely turning the main target ring. The Tamron has a non-linear gearing which is dependent upon the velocity you flip the main target ring. This permits for exact guide focus however makes clean focus pulling for videographers virtually not possible. The main target ring on the Sony has a linear gearing with an extended throw of 150 levels plus a spotlight maintain button which might be assigned different duties within the digicam menu. Each the Sony and the Tamron don’t have any distance or dof markings. [+]
Covers full body or smaller. Identical with the alternate options. [+]
Value: 400 EUR (incl. 19% VAT) / 349 USD. This can be a very inexpensive lens in comparison with the Sony with an inventory worth of 1100 EUR / 899 USD. [+]
The Tamron has no pouch however the lens hood is included, reversible for transport. The Sony comes with a tender pouch and lens hood. 
Aperture ring: no, which is regular for many trendy lenses. However the Sony has one with 1/Three cease clicks which might be turned off for steady, clean, and noise-free operation. 
Sealing: sure, a rubber grommet on the lens-mount plus additional particular weather-sealing all through the development. Identical for the Sony. [+]
The rating within the “features-department” of 0[-]/4/8[+] reveals that the lens has characteristic set: some great benefits of the Tamron are its small dimension, low weight, low worth, and a 1:2 most magnification. The main draw back is its comparatively gradual focal ratio of f2.8.
Two methods to go 20mm on Sony Alpha mirrorless cameras
Above: Sony FE 20mm f1.Eight G (left), Tamron 20mm f2.Eight M1:2 (proper)
The marketplace for ultra-wide prime lenses of 18-21mm focal size presents many selections with autofocus lenses from Sony (FE 20mm f1.Eight G), Tokina (FiRIN 20mm f2.Zero FE AF), Samyang (AF 18mm f2.Eight FE), and Sigma (20mm f1.Four Artwork), plus guide focus lenses from Zeiss (Loxia 21mm f2.8), Viltrox (20mm f1.Eight Asph), Voigtländer (Shade-Skopar 21mm f3.5 Asph and Nokton 21mm f1.Four Asph), and Samyang once more (20mm f1.Eight ED AS UMC). However none of those lenses comes near the utmost magnification of 1:2 which the Tamron presents.
Let’s have a more in-depth take a look at a few of these with autofocus:
- Sony presents the FE 20mm 1.Eight G from 2020 for 1100 EUR / 900 USD. It presents a multiple cease brighter focal ratio and is bigger and heavier than the Tamron however not overly so. For the cash you additionally get a de-clickable aperture ring and a focus-hold button which might be assigned different duties within the digicam menu. See my Sony FE 20mm 1.Eight G assessment the place it got here Extremely Really helpful.
- From Sigma there’s the 20mm f1.Four Artwork, a typical DSLR design from 2015 which is now additionally obtainable for Sony E-mount. It presents two stops extra mild gathering energy however consequently is an enormous lens weighing properly above 1kg. Sigma presents the distinctive (payed) service to have the mount swapped when you change our bodies however the lens doesn’t have a normal filter-thread and there’s no climate sealing on the lens-mount. For extra particulars take a look at my Sigma 20mm f1.Four Artwork assessment and the direct comparisons in my Sony FE 20mm 1.Eight G assessment.
- Samyang/Rokinon has the AF 18mm f2.Eight FE for 350 EUR /USD. This lens is even smaller (64 x 61mm) and lighter (145g) than the Tamron however its close-up capabilities are meager: it solely reaches a most magnification of 1:11. At 18mm focal size it presents a 6 levels wider angle of view.
Lastly you may also contemplate a zoom lens just like the Tamron 17-28mm f2.Eight Di III RXD (Modell A046) in its place. It has the advantage of a 1.6x zoom vary protecting a big selection of very helpful focal lengths on the large finish at a relentless f2.Eight focal ratio. It’s naturally bigger and heavier than the Tamron 20mm f2.Eight M1:2, however at 73 x 99mm and 420g (14.Eight oz.) nonetheless very compact for an f2.Eight zoom lens. And it presents good to superb optical efficiency which acquired it a advice in my Tamron 17-28mm f2.Eight Di III assessment. Its worth of 850 EUR / 900 USD places it properly above the 20mm f2.Eight M1:2 however this zooms rolls Four standard focal lengths up into one.
Focus accuracy and repeatability is important to persistently produce sharp pictures. Repeatability (the accuracy of deal with the identical topic after repeated focus-acquisition) of this lens was unsatisfactory with my first check copy. However on a second copy of the lens it was superb (measured 99,0% in Reikan FoCal) with no outliers over a collection of 40 pictures. And the second copy additionally confirmed no focus variation whether or not the lens focuses from a more in-depth distance or from infinity.
The lens took round 1 sec to maneuver from infinity to 0.25m (1:10 magnification) till the digicam sounded the “in focus” beep. But it surely hunted visibly a bit afterwards across the level of sharpest focus and solely then did the shutter launch. The whole time from urgent the shutter to taking the shot was round 1.6 sec which could be very gradual and particularly annoying when taking pictures (quick) transferring topics. This along with the pattern variations makes me suspect that Tamron’s OSD (Optimized Silent Drive) is extra optimized for price than for efficiency. The Sony then again focuses shortly and with out searching in round 0.7 sec.
The main target ring of the Tamron is 17mm large with a rubberized floor. It strikes tremendous clean and may simply be operated even together with your pinky. The frontend of the lens extends 7mm when targeted to minimal object distance however this doesn’t change the general size of the lens (see under).
AF-operation of the lens is barely audible from the surface. However when you report video with the built-in microphone the AF-drive makes a lightweight click on at first of motion.
The lens reveals some focus respiration: when I adjusted the main target from infinity to 0.25m on the brand new Tamron I measured a 4.2% improve in magnification, just like the Sony. That is fairly seen and will not please videographers.
Subsequent take a look at my high quality outcomes!