Fstoppers Reviews the Tamron 11-20mm f/2.8 Di III-A RXD Lens, the Company’s First for Canon RF

There’s always been a gaping hole in Canon’s APS-C strategy. While there are plenty of competent APS-C cameras from the company, it hasn’t always produced the professional lenses to match the bodies.

That’s where the Tamron 11-20mm f/2.8 Di III-A RXD lens fits in. It’s a super-wide, fast zoom lens designed to be the small-format equivalent to the big, heavy and expensive full frame wide angle zooms. Think something like Canon’s RF 15-35mm f/2.8 L IS USM lens, but at a fraction of the size, weight and cost.

Fundamentally, a lens like this raises the question of whether APS-C is a “stepping stone” format to a larger sensor camera or whether it is an independent option in its own right. Canon has occasionally shown a commitment to the latter philosophy, releasing an occasional fast zoom, but for the most part, it ceded that territory to third-party lens manufacturers.

So while Canon may not be directly answering the question, it’s something I’ll aim to do in this review.

Build Quality

From a build quality perspective, it’s a beautiful lens, as it should be for a $659 APS-C piece of glass. Tamron’s been on a tear for quite some time, matching the look and feel of (and in some cases exceeding) first-party manufacturers. The company even thoughtfully includes a lens hood in the package, something Canon makes you pay for in anything less than an L lens.

In the case of this particular 11-20mm lens, the metal-and-plastic construction is solid, feels good in the hand, and has all the necessary coatings and gaskets for the company to claim “weather-sealed construction.” That’s not something I put to the test in the lens the company loaned me for this review, but it’s comforting to know that if it starts raining, I probably don’t have to put this one back in the bag right away. Just make sure that you have a matching weather-sealed body. Three out of the four Canon APS-C bodies that this lens is designed for don’t have weather-sealing (the EOS R7 being the exception). I tested on an EOS R50.

The lens itself is a diminutive 3.3 inches long and weighs 12 ounces. Coupled with my R50, the entire package is just over 1.5 pounds. The nearest comparison I have in my full-frame lens bag is the Canon EF 16-35mm f/4L IS USM Lens, and that one alone is 1.35 pounds and 4.5 inches long. On an R5 body with the Canon Mount Adapter EF-EOS R, it’s just over 3 pounds, more than double the weight of the Tamron/R50 setup. Here’s how that looks in practice:

Other features and an omission: The lens has a USB-C port on the side for firmware updates and features a welcome 67mm filter thread. That’s a lot smaller than the more common 77 and 82mm threads on full frame lenses, and it makes for cheaper filters all around. Sadly, as the design is one shared across multiple systems, there is no control ring for additional camera functions around the barrel, like on many Canon RF lenses. It’s a pretty no-nonsense design with the only switch being for manual or autofocus. Surprisingly, some of Canon’s own lenses, such as the Canon RF-S 18-150mm f/3.5-6.3 IS STM Lens eliminate this basic function and force you to dig through menus to accomplish switching to manual focus, so it's good of Tamron to include that. I found myself using the switch all the time for landscape photography, something this lens is ideally suited for. The focus ring turns smoothly and allows for fine manual focus adjustments.

The lens isn't stabilized, but on a wide angle, that's less of a problem than on a telephoto. I'd rather take the weight and size savings gained by ditching stabilization on a wide angle lens.

There's really not much one can fault here about the construction of this lens.

Image Quality

There’s more to the lens than just good looks, however. From an image quality perspective, it acquits itself well. It’s nice and contrasty, and color is beautiful and accurate. The lens exhibits some typical ultra-wide angle lens issues. It vignettes a bit at f/2.8, and sharpness falls off just a bit in the corners, but all of that is gone by f/5.6. The lens is tack-sharp at the center even wide open. There’s some typical wide angle distortion at the edges of the frame as well. You can see a comparison of that here:

The distortion and vignetting are easily corrected by picking the right profile in Adobe Camera Raw. The lens is a very recent release (Tamron’s first for the RF system, actually), so it doesn’t default to a profile for correction at the time of this article, but the lens has been made for other systems, and the profile exists if you pick it manually. It worked wonders to correct distortion, as you can see from the horizon in this photo:

While I’ve tried all manner of ultra-wide lenses that Canon itself has made for the APS-C format, from the Canon EF-S 10-18mm f/4.5-5.6 IS STM Lens, to the ever-so-slightly higher-end Canon EF-S 10-22mm f/3.5-4.5 USM Lens, to the Canon EF-M 11-22mm f/4-5.6 IS STM Lens, all of these lenses have, ultimately been disappointments that have led me to reach for my full-frame f/2.8 and f/4 wide angle lenses with red rings around them. It was not just the lack of a constant aperture, but lots of chromatic aberrations and softness as well.

But with the Tamron, having that fast, constant aperture in a portable package made me want to carry it more. A lens is no good if the weight discourages you from carrying it. That’s probably the best case to be made for the Tamron. It packs a large punch in terms of image quality and usability in a smaller package than you’d need for full frame.

And even though the lens has inherently more depth of field because of the APS-C format, it still can get impressively close for a wide-angle lens, resulting in some ability for shallow depth of field:

You're not giving up a lot by not going full frame these days, with modern APS-C cameras. It makes the more attractive option in 2024 than it would have been in the past.

Who Is It for?

This is where I struggled most in my thoughts about this lens. When you’re a Fuji shooter, buying this lens in the X-mount makes sense. Fuji puts the entirety of its rear end into its APS-C cameras because it’s not pushing you into its full frame cameras that don’t exist. Fuji APS-C cameras are treated as professional-grade cameras by the company.

Canon doesn’t quite seem to follow the same philosophy, and so it puts third-party lens makers such as Tamron, Sigma, Samyang and others in a bit of a pickle: This RF-S lens is, by all metrics, a great lens. Though it’s carried over from other mounts, more or less, Tamron has brought their A-game to this lens as it has many of its other recent releases. But, whereas a professional wedding shooter, astro photographer or landscape photographer shooting a Fuji camera could make an easy case for an APS-C only lens of this caliber, the water is muddied when there are full-frame options in Canon’s lineup that are not much far off, cost-wise. Here’s a comparison of the R50 to the R5 shooting the same scene, at the same settings, with the aforementioned 16-35mm lens on the R5:

The Tamron holds its own against the full-frame camera and lens combo, but R% and 16-35mm combo does win a little bit on detail, especially viewed at 100%. That's not a knock on Tamron; It’s more of an indictment about how even the highest-end APS-C cameras from Canon pull punches, not approaching the resolution or features of something like an R5. I’m aware that this is an R50 and not an R7, but there’s still a wide resolution and feature gap between even those two cameras (45 MP for the R5 vs. 32.5 for the R7, with the R50 clocking in at 24.2 MP).

And while we’re talking about indictments, Canon continues to restrict companies such as Tamron from making full-frame lenses for the RF mount. That’s really what’s forcing Tamron’s hand here, along with other third party lens manufacturers. It does explain how third-party manufacturers make some very professional-grade and esoteric lenses for the APS-C mount.

So who, then, would benefit from such a lens? Photojournalists aren’t always shooting in the dark like wedding photographers, and so they could reap the mobility and stealth benefits of using such a lens on an APS-C body. Hobbyists committed to the format could certainly benefit from a fast, ultra-wide zoom. It’s a step up in terms of image quality from any of the kit-grade lenses that Canon makes for the RF-S mount, so it’s an upgrade path for amateurs looking to add more professional polish to their work as well. And finally, this makes a great travel lens owing to its size and weight, or lack thereof.

All of those groups are certainly a large slice of the photographer pie, but it would be great to see what Tamron could do if it were allowed to unleash its full frame lens lineup on the RF mount. That said, this is certainly a promising start.

Conclusion

While it’s a bit of an odd duck when placed in the Canon ecosystem, there’s a place for a solidly-built, fast-aperture ultra-wide lens in the APS-C format. While it’s not necessarily the easiest on the wallet for what it is, it’s certainly worth the money based on its image quality and portability for this type of lens. It’s definitely an excellent first lens for the company’s RF efforts. For Canon shooters, the biggest decision in buying this lens will be whether they intend to commit to Canon's vision of what APS-C cameras should be.

What I Liked

• Good build quality; feels good in the hand
• Good image quality
• Very portable and lightweight

What I Didn't Like

• The $659 price tag is skirting awfully close to full frame professional ultra-wide territory, which on a full frame Canon body will give you more detail at the expense of size and weight
• No control ring

Purchase

You can purchase this lens for $659 at this link here: Tamron 11-20mm f/2.8 Di III-A RXD Lens (Canon RF).