Tamron's 11-20mm F2.8 Di III A RXD ($829) will be the direct competition to Sony’s 10-18mm F4 OSS. Tamron's lens has better build quality, including the lack of weather protection and brighter F2.8 optics. If you want a wider view of your camera, this lens is the one to buy. However, vloggers might prefer the Sony 10--18mm because it has stabilized optics.
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Made for Outdoor Photographers
Only available for Sony mirrorless cameras, the Tamron 11-20mm. The optics cover the APS-C sensor used in models of the a6000 series as well as the ZV-E10 vlogging cameras.
It maintains an F2.8 maximum aperture across its focal range, netting twice as much incoming light as the Sony E 10-18mm F4 OSS. The Tamron lens is bigger all around because of it, about 3.4 by 2.9 inches (HD) and 11.8 ounces, to the Sony's 2.5 by 2.8 inches and 9.4 ounces. You can see the two side by side in the photo above.
It is protected by a polycarbonate barrel and the Tamron feels stronger than its aluminum counterpart. The Tamron is also more protected. Tamron also includes splash and dust protection, as well as anti-smudge fluorine in the front glass.
The 11-20mm supports the 67mm filter size, and there's a lens hood included for some extra protection from stray fingerprints and lens flare. Front and rear lens caps are included, but Tamron doesn't bundle a soft case or pouch—you're on your own there.
The controls on the lens are simple and have a few rings that adjust focus and zoom. You can feel the raised edges of rubber on the zoom control, which is located mid-barrel. You can find the focus ring a bit further back and it has plastic ridges. You will need to go into the camera menu in order to switch focus modes.
Autofocus is quick and quiet, a good fit for video and stills alike. I used it in continuous focus with the ZV-E10 for vlog footage and found it to be a good fit. There's a little focus breathing visible when racking from close focus to infinity, but it's not distracting for shots where the subjects is only moving slightly away or toward camera.
While the focus ring is easy to turn, it has enough resistance to allow for subtle adjustments to your focus when you work manually. A rapid turn of the focus ring will result in a dramatic shift. Slower, more deliberate movements are used for fine adjustments. This is useful for still images, however videographers prefer to use a more linear focus response.
Wide lenses don't net macro results given their big angle of view, but most designs support very close focus. The lens locks as close as 5.9 inches, so you can get really close to a subject and capture a big swath of background behind it. When zoomed in, the lens nets 1:4 life-size reproduction at its closest focus point.
Sony's E 10--18mm F4 zoom has optical stabilization, but it isn’t available. This is an important point because Sony has only two APS-C cameras that have stabilized image sensor, the a6500 or a6600. The Tamron is a perfect match for these models, which include five-axis IBIS as well as splash and dust protection. The 10-18mm lens is recommended for long exposures and handheld video if your Sony does not have stabilization.
The lens is made for APS-C sensor cameras, but mounts on full-frame models too. I used it with the Sony a7R IV in the field and for lab tests. The a7R IV's 60MP crops down to 26MP in APS-C, just about matching the resolution of the a6100, a6400, a6600, and ZV-E10. You have the option of using the lens in full-frame mode too, but the optics don't cover a full-frame sensor, as you can see in the uncropped, full-frame photo from the a7R IV above.
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The Lab
We used the 26MP APS–C mode on our a7R IV for lab testing. To photograph our resolution chart, we reached out to Imatest for analysis. This pair produces strong results. The central resolution of 11mm at f/2.8 is exceptional. While there are some drops in clarity towards the edges, the images still display strong detail.
There is some field curvature at play here—our up-close resolution testing shows very low numbers at the edges of the frame because our test chart is flat, but they don't reflect real-world results. For crispest landscape photos, you'll want the focal length to be f/5.6 and f/8.
Resolution remains strong zoomed in. Center resolution is outstanding at 15mm f/2.8 and remains very good toward the edges. We see the sharpest results from edge to edge at f/8, as good as you can expect from a 26MP sensor. The story is the same at the 20mm setting—the lens leaves you wanting nothing in terms of resolution.
Tamron employs rounded aperture blades. This choice draws beautiful defocused backgrounds close up, but does not produce the most stunning sunstars. The effect is obtainable—multi-point starbursts are visible around the sun and other bright highlights starting at f/11, but aren't as clearly defined as through lenses with simpler apertures like the manual-focus, full-frame Venus Laowa 10-18mm, or exotically priced alternatives like the Sony FE 12-24mm F2.8 GM.
Adobe Lightroom already has a correction profile for the 11-20mm, so if you use it to process your Raw images you won't have to fret about any barrel or pincushion distortion, or a vignette. You do see it in uncorrected photos—there's some barrel distortion at 11mm and pincushion at 20mm, as well as darkened corners at f/2.8. Digital corrections make them invisible for the most part; if you use your camera in JPG mode they're applied by default.
A Wide All-Weather Zoom
The Tamron 11-20mm F2.8 Di III-A RXD fills a notable gap in Sony's APS-C lens catalog—a wide, made-for-APS zoom with dust and splash protection. The Tamron 11-20mm F2.8 Di III-A RXD has F2.8 optics that are not available with the Sony E 10-18mm F4 OS, and a stronger, weather-protected construction. It's an important feature for outdoor photographers, especially those using the a6500 and a6600, Sony's two dust-and-splash-protected APS-C cameras.
It omits optical stabilization. That's less of a concern for a6500 and a6600 owners, as both models include stabilized sensors. But for handheld video and longer exposures without a tripod, a6400 and a6100 photographers, and ZV-E10 vloggers, there's some reason to spend more on the Sony 10-18mm.
We like the Tamron 11-20mmF2.8 Di III A RXD better than those use cases. The optics of the Tamron 11-20mm F2.8 Di III-A RXD are excellent. It is slightly less expensive than Sony's 10--18mm. Additionally, it has twice as much light gathering, which can be a benefit for night skies, but it does not sacrifice wide-angle coverage. It's a great addition to the APS-C Sony cameras.