2024 has been the year where Canon has finally, grudgingly, let a third party lens makers creep in to their RF mount, though with one huge caveat. There are still (absolutely!) no full frame lenses from third parties allowed, but Canon is opening up the RF/RF-S mount to APS-C lenses. Earlier this year I reviewed a few of the first Sigma lenses to come in an RF mount, and the Tamron 11-20mm F2.8 RXD becomes the first Tamron lens to arrive on the platform. This is great, as it provides another high quality wide angle option for Canon shooters to consider. But is there enough here to bypass the equally interesting Sigma 10-18mm F2.8 DN lens that is also now available on RF? Find out in either my video review or in the text review below.

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Thanks to Tamron USA for sending me a loaner of this lens.   As always, this is a completely independent review.  All opinions and conclusions are my own. *The tests and most of the photos that I share as a part of my review cycle have been done with the APS-C mode on my 45MP Canon EOS R5, which I reviewed here.

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Tamron loves its initials in their lens names, so let’s sort out that alphabet soup.  Di III is their designation for a mirrorless lens design, and, in this case, the addition of -A at the (Di III-A) refers to their development for APS-C mirrorless.  RXD refers to the focus motor, and means Rapid eXtra-silent stepping Drive.

As with the Sigma lenses I’ve reviewed before, Canon is explicitly keeping you out of the full frame protocols. I don’t own a Canon APS-C camera, so I’m doing this review on the APS-C mode of my full frame Canon EOS R5. Typically I can evaluate full frame coverage on Sony or Nikon, but here all options but the 1.6x APS-C crop are greyed out. Canon is making SURE you don’t enter that sacred full frame space under any circumstance!

Canon is unique amongst other brands in that their APS-C crop is tighter than other brands. It is 1.6x rather than 1.5x, meaning that the effective focal length of the lens changes a bit in this application. Whereas it will be 16-30mm frame equivalent on 1.5x, it will be 17.6-32mm on Canon. That’s unfortunate with a wide angle lens, as typically your priority will be to have as wide of framing as possible.

The 11-20RF covers a very useful range nonetheless, giving you a variety of framing options at 11, 14, 16, 18, and 20mm (the marked positions on the zoom ring):

The 11-20RF is priced at $659 USD, which is identical to where the Sigma 10-18mm F2.8 DN is priced (my review here) and considerably more expensive than the roughly $300 budget Canon RF-S 10-18mm F4.5-6.3 IS STM lens. It it worth the price premium over the Canon, and should it be considered instead of the Sigma? While this is the third platform that I’ve reviewed this lens on (Sony E and Fuji X previously), so there will be some recycled material in this review. But I will try to specifically address those questions in the RF version of the review.

Build and Handling

The Tamron 11-20mm RXD certainly hits a sweet spot for size and weight for a wide angle zoom. It feels reasonably compact on my frame Canon EOS R5, but I’ve also reviewed it on smaller bodies on Sony, and it worked fine there..  It is 2.9″ (D) x 3.4″ (L), or 73 x 86.2 mm according to the specifications, as even though the Canon RF mount is wider in diameter than the Sony E or Fuji X mounts, this isn’t the widest part of the lens.  Like most of Tamron’s mirrorless lenses it has a 67mm front filter thread which allows filters to be shared across almost all of Tamron’s other options for the platform (excluding the much larger 150-500mm, obviously!)  The weight is 11.8 oz (335 g), making it the heaviest of the three wide angle zoom options on Canon RF-S. The Sigma is 270g, while the “slow” Canon lens is just 150g.

I call the Canon “slow” because it starts at a rather dim F4.5 at 10mm and quickly arrives at a maximum aperture of an even slower F6.3 later in the zoom range. That’s a huge disadvantage relative to the Tamron and Sigma lenses, that have a constant F2.8 aperture throughout the zoom range. F2.8 lets in twice as much light as F4, which means that at best the Canon will be 1 1/3 stops dimmer and at worst 2 1/3 stops. That means that the Tamron or Sigma lenses will be much, much more useful in low light situations. Canon tries to compensate by including IS (Image Stabilization) in their lens, but that won’t always help as it doesn’t stop movement of subjects, meaning that you would still have to jack up the ISO to freeze action. I would much rather have a faster lens like the Tamron.

While the depth of field is more equivalent to a full frame F4 lens, the F2.8 aperture will always have the light gathering capability of an F2.8 lens (regardless of whether attached to APS-C or Full Frame), meaning that the 11-20mm RXD has the advantage of being able to have more in focus at larger apertures but all the light gathering potential of an F2.8 lens – which can be a big help in low light conditions.

This is a new lens on Canon, but it has been out on Sony since 2021. That means that this lens comes from an older stage of Tamron’s development cycle and design language, but Tamron had made a key update to the RF version in that it has an AF | MF on upper left side of the lens. I appreciate having the AF | MF switch, and that alone makes this perhaps the best version of this lens.

Tamron has also added a weathersealed USB-C port which will allow you to use Tamron’s Lens Utility software that is available (for free) from the Android app store or you can visit this page to download the software and/or get more information:

Right now this only allow for firmware updates (no customization as with some lenses), but I like having future options.

The position of the two rings on the 11-20mm is reversed relative to the 17-70mm, which is unfortunate for those who will buy both lenses to use as a kit (I’m assuming the 17-70mm will soon be available on RF too).  The closer (and wider) of the two is the zoom ring.  The zoom ring has a rubberized, ribbed texture, is easy to find by touch, and moves smoothly through the zoom range without any sticking points.  The inner barrel will extend about 2cm at the 11mm position:

The lens will be at its fully retracted position at 20mm.

While many would prefer an internally zooming lens, thus far all of these Tamron zooms have been externally zooming, though they must be doing a fairly good job of sealing the lenses, and I’ve heard little anecdotal reports from buyers about getting dust inside of them.  The inner barrel extends smoothly and without any wobble.

The second ring (nearer the front of the lens) is the manual focus ring.  This (like all mirrorless lenses) is focus-by-wire, meaning that focus input on the focus ring is routed through the focus motor to move the elements.  Manual focus feel is fairly light and without a lot of tactile feedback.  Typical manual focus aids are all available, as Tamron lenses on Canon RF function largely like native lenses.

Tamron has included a shallow, petal-shaped lens hood with deep ribs inside that disrupt stray light bouncing around.  It’s plastic and lightweight, but the quality of the plastics is apparent by feel.  It doesn’t feel as cheap as some hoods that I see.  It feels like it could take a few bumps without cracking.  Due to the wide-angle nature of the lens, the lens hood is fairly wide, so it doesn’t reverse completely flush along the sides of the lens for storage.  

The lens’ housing is a nice grade of engineered plastics with a satin finish.  There’s a platinum-colored accept ring right near the lens mount.  Nothing fancy on the outside, but the lens “look” is clean and it looks nice mounted on the camera.

As noted, however, the good stuff is inside.  There’s a rubber gasket at the lens mount that is the outer evidence of the weather sealing inside, and this is diagram from Tamron shows that there are a total of seven seal points in the lens.  This is capped off by a nice fluorine coating on the front element, which not only helps protect it from scratches but also makes it water and fingerprint resistant and thus easier to clean.

Tamron’s recent trends regarding MFD (minimum focus distance) hold true here, as the lens sports two different MFDs for wide (0.15m/5.9″) and telephoto (0.24m/9.4″).  Both are pretty close, frankly, with the 11mm position requiring you to be nearly on top of your subject (the length from the sensor to the end of the lens WITHOUT the hood is 12cm, leaving you only 3cm of working room to your subject.  If you leave the hood on, that length grows to 14.5cmm, leaving you a few mm of working room.  It will be almost impossible to avoid shading your subject with the lens attached, so remove the hood to give you a bit more working room.  Even so, I found it almost impossible to properly light my test chart even moving my lights right in, as this is what MFD looks like: 

Should you be able to get that close, you get as high as a 0.25x (1:4) magnification figure, which looks like this.

Being able to pull off shots that close in the real world are rarely going to happen, so I consider that 0.25x figure to mostly be marketing.  You can still get a reasonable magnification by backing up a bit, though.  My preference is just to use the 20mm position or somewhere in between.  The telephoto end gives you a better working distance and better results in terms of sharpness, but unfortunately the magnification figure drops to a much more pedestrian 0.13x, though even that figure is better than the Fuji 8-16mm (0.10x) and only slightly lower than the Fuji 10-24mm (0.16x).  The magnification at 20mm looks like this:

You’ll note that the 20mm position gives a much flatter focus plane. The telephoto magnification figure is a bit lower, but achieving the result will be much simpler in the field and probably much more satisfying in the process.  I find a nice compromise is to shoot somewhere around 16mm, as you can get closer than 20mm, achieve a higher magnification level, but without being right on top of the subject like at 11mm. 

As is common with wide angle lenses, Tamron has reduced the number of blades from nine to 7 rounded blades.  A lens like this is less about bokeh and more about being able to produce nice sunstars, and the seven bladed aperture produces a cleaner looking sunstar.

Tamron touts the flare resistance of this lens, but it isn’t perfect, as you can see. We’ll dive into that more in the image quality section.

The Tamron 11-20mm RXD is a simple lens in terms of design and features, but at the same time I’ve had no long term issues with Tamron lenses just like this one.  They’ve held up fine and get the job done, though I do miss some of missing features.

Stills Autofocus

As noted, the 11-20RF is equipped with Tamron’s Rapid eXtra-silent stepping Drive (RXD), and this will be the first time that I’ve used a native Tamron lens on Canon RF. I wasn’t surprised to find that autofocus worked great, however, delivering fast and accurate results.

Canon’s focus systems are pretty great, and the Tamron works just like a better native lens, with quick, silent focus that is nearly instantaneous in making focus changes.

Eye Detect works fine (as it does almost universally now), though with a wide angle lens like this you have to be pretty close for the eye to occupy a large enough part of the frame to show active tracking.  If you are close enough, however, the “stickiness” of the box on the eye is fairly good and will follow the subject around. 

Bottom line is that the Tamron 11-20RF works a treat on Canon. All good.

Video Autofocus

That goodness extends to video AF as well. Focus pulls were fantastic, with smooth confidence and no visible steps. Focus breathing is low, making this a very nice lens for pulling focus with.

My “hand test” where I alternately block the view of my face with my hand and then remove went fine overall, though it’s a little hard to block the camera’s view when the angle of view is so wide!

More subtle focus transitions during video capture were generally smooth, and while occasionally focus will stick on a subject when you want it to move, I felt in general that focus worked well. This would be a nice vlogging lens, too. Here’s a still from one of my video clips:

This pairing gives me a lot of hope for Tamron lenses on Canon RF. Focus seems extremely natural and smooth.

Image Quality Breakdown

I’ve reviewed the optics of this lens twice previously, and nothing has changed. This is an optical formula of 12 elements in 10 groups, with 5 of those being exotic elements (molded glass aspherical, hybrid aspherical, and Low Dispersion).  Here’s a look at the optical design and MTFs:

If you understand MTF diagrams, you will note that these are very good looking MTFs for a wide angle zoom lens.  Tamron does its MTFs wide open, and the surprising thing about the 11mm result is that there is actually a bit of dip in resolution near the mid-frame position with the corner resolving better than the mid-frame area (though contrast is must lower in the corner relative to the mid-frame).  The 20mm result shows a more typical slide towards the edge of the frame. 

I didn’t find it hard to get results that were sharp across the frame.

Results at 20mm, F2.8 also looked very crisp and detailed.

My vignette and distortion tests showed largely expected results. Here’s a look at 11mm:

Distortion is a constant on all three platforms, with a mildly complex barrel distortion that corrects fairly well with a +9. The standard correction profile will do a slightly better job. Vignette falls in between my results on Sony and Fuji at a +71. Fuji was the worst at a +78, with Sony far better at +46. In my experience lenses tend to perform best in this metric on the platform they were first designed for (Sony, in this case). In both of these metrics, the Tamron easily outperforms the Sigma 10-18mm on RF, as I had to dial in a +23 to correct the barrel distortion and had to max out the vignette slider.

Here’s what things look like at 20mm:

There is a mild amount of pincushion distortion that required a -5 to correct and a bit less vignette, requiring a +54 to correct.

I saw good results with longitudinal chromatic aberrations (LoCA), with very crisp results, good results, and strong contrast even at F2.8:

There is a mild amount of lateral style fringing near the edges of the frame that you can only see at high levels of magnification.

Colors were rich and images looked nice, in my opinion.

Here’s another sample on Canon:

I’ve already tested this lens on the most challenging platform for APS-C, which is Fuji’s 40MP sensor. Canon’s current highest APS-C resolution is the 32.5MP sensor found in several models. Unfortunately I don’t have access to one of those models, so I’m testing on the APS-C mode of my Canon EOS R5. That’s a very undemanding 17MP, so I’ll focus new information in this section on the vignette performance, which will be unique to Canon. Canon results will fall in between my Sony tests (24MP) and more extreme Fuji tests (40MP). If you have a lower resolution camera (24MP), then look at the results in the Sony test here. If you have the higher resolution sensor, you might want to check out the Fuji findings here, though with the understanding that you’ll see better apparent sharpness results on Canon because the pixel density is lower and because it is much easier to sharpen Canon files.

I noted that I would dive into flare resistance a bit more. I felt like flare resistance at larger apertures was actually pretty good. This shot at 20mm, F2.8, doesn’t show any negative impact from shooting right into the bright directional sun.

This F2.8 wide shot shows a bit of ghosting in the trees to the right of sun in the frame, but nothing too bad.

Stopping the lens down introduces a few more prismatic spots, though nothing too destructive.

The performance actually feels better than what I found on Sony. Perhaps coatings have improved a bit. I feel like contrast holds up really well with the sun in the frame.

Coma performance is quite, with night sky images looking clean other than a bit of “star-stretching” in the corners.

I really liked the Sigma 10-18mm on platforms like Sony and Fuji, but I was frankly a little underwhelmed by the lens on Canon, for some reason. I like the Tamron better here, and a lot of that came down to how the colors of the optical glass meshed with Canon’s color science. The Tamron seems like a better fit.

If you want to see more images, check out the RF image gallery here.

Conclusion

The Tamron 11-20mm F2.8 Di III-A RXD is a welcome addition to the Canon RF platform, as it gives another legitimate wide angle zoom option. It’s an important lens, in that while it isn’t new (on other platforms), it is the first Tamron lens to come to Canon’s RF platform. Here’s the hope that this is the first of many, including (eventually) some full frame options.

Like the Sigma 10-18mm F2.8, the Tamron isn’t cheap, costing twice as much as Canon’s own slower and plasticky RF-S 10-18mm. But it is also the superior optical instrument in build, function, and aperture speed.

Not everyone will want to spend over $600 for this lens, but those that do will find a lens that they will invariably enjoy, providing fast autofocus, good handling, and a very good (and consistent) optical performance. I’d say that it would currently be my choice, and that’s about as good a recommendation as I can give.

Pros:

• Finally a Tamron on Canon RF!
• Great wide angle zoom range
• Maintains F2.8 aperture
• Relatively compact and lightweight
• Good build with weather sealing
• Fast, quiet, and accurate autofocus
• Shares a 67mm filter thread with other Tamron lenses on Sony
• Exceptional optical performance
• Good coma control
• Strong aberration control

Cons:

• No aperture ring
• Corners lag behind the center a fair bit
• Relatively expensive compared to the Canon RF-S 10-18mm

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GEAR USED:

Purchase the Tamron 11-20mm F2.8 RF @ B&H Photo | Adorama | Amazon | Camera Canada | Amazon Canada | Amazon UK | Amazon Germany

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