Tamron 11-20mm F/2.8 Di III-A RXD Lens Review

An ultra-wide-angle zoom is usually the second or third most essential lens in the kit. The 11-20mm F/2.8 Di III-A RXD is Tamron's APS-C option to fill this need, and it is a great choice.

While the APS-C image circle is huge relative to that of phone cameras, it is small compared to the full-frame circle. Wide-angle APS-C lenses, including this one, greatly benefit from the reduced element size requirements. The Tamron 11-20 remains compact and light despite it having a wide f/2.8 aperture over the entire focal length range. The wide increases this lens's versatility into low light conditions and enhances the lens's subject-isolating background blur potential.

This is another well-designed and constructed Tamron lens that features a high-quality AF system and superb image quality. Of course, it has the great value price so synonymous with the Tamron brand.

Focal Length Range

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The focal length range is the first aspect to consider for zoom lens selection. Focal length drives subject distance choices, which determine perspective.

The 11-20mm angle of view equates to that provided by a 16.5-30mm full-frame lens on a full-frame camera, ranging from ultra-wide to moderately wide. Notably, this range is an ideal complement to that of the Tamron 17-70mm f/2.8 Di III-A VC RXD Lens.

Often, one cannot back up far enough to get a large subject or vast scene in the frame, and in that case, an ultra-wide-angle zoom lens is the right choice. When a foreground subject is to be emphasized, rendered large in relation to a vast background (potentially in sharp focus), moving in close with an ultra-wide-angle zoom lens is again the right choice.

What subjects are this lens ideal for? That list is massive. Let's discuss a few of the genres most photographed by this lens class.

Landscape and astrophotography are great uses for this range. The 11-20mm focal length range is a great choice for capturing the beauty of our planet and beyond. It gives us a reason to go out and enjoy the great outdoors, to address our NDD (Nature Deficiency Disorder).

Another genre of photography with huge subjects, often including some landscape, is real estate photography, and this lens is a great exterior and interior focal length range choice for this use. Directly related to real estate photography is architecture photography, and this lens will take in massive structures even when a short working distance is available.

Usually, the structures we photograph are built for people, and people are also a good subject for this focal length range. However, avoid getting too close to people when this lens is mounted.

While a close-up perspective can look incredible in a wide-angle landscape scene, it is generally to be avoided when a person is the primary subject. We do not typically look at a person from really close distances, and if we do, that person becomes uncomfortable with us being in their personal space (and even more so when a camera is in hand). When we look at photos of people captured from close distances, certain body parts (usually the nose) start to look humorously (to some) large.

Unique portrait perspectives can be fun, but this technique quickly becomes overused. Get the telephoto lens out for your tightly framed portraits.

Still, wide-angle focal lengths can be a great choice for photographing people. Simply move back and include people in a larger scene, creating environmental portraits.

The 20mm focal length provides a natural perspective and is a good choice for full-body portraits. The 11-20mm focal length range also works well for small to large groups. Note that group photography requiring an ultra-wide-angle focal length to fit everyone in the frame often leaves those in the front row appearing considerably larger than those in the back row (the subject distance varies by a significant percentage). Back up or move the subjects closer together (front to back) to reduce the multi-row perspective issue.

The 11-20mm focal length range is a great option for the wide work at weddings, family gatherings, and other events and for photojournalism and sports photography needs. The 20mm end provides especially good general-purpose utility.

This lens, including the focal length range, size, and weight, is an ideal candidate for self-recording (vlogging). The following images illustrate the 11-20mm focal length range:

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Most photographers will find it imperative to have coverage of this focal length range.

Max Aperture

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The lower the aperture number, the wider the opening, and the more light the lens can transmit to the imaging sensor. Each "stop" in aperture change (full stop examples: f/2.0, f/2.8, f/4.0) increases or decreases the amount of light by a factor of 2x (a substantial amount).

The additional light provided by wider aperture lenses permits freezing action and handholding the camera in lower light levels and allows lower (less noisy) ISO settings. In addition, increasing the aperture opening provides a shallower DOF (Depth of Field) that creates a stronger, better subject-isolating background blur (at equivalent focal lengths). Often critical is the improved low-light AF performance availed by a wide-aperture lens.

In an 11-20mm lens, f/2.8 is relatively wide. A wide aperture's disadvantages are related to (often significantly) increased lens element size and include larger overall size, heavier weight, and higher cost. Despite its relatively wide aperture, this APS-C format lens maintains the small size, light weight, and lower cost advantages.

Wide apertures are not always required, especially in the ultra-wide-angle focal lengths. Motion blur is caused when subject details cross over imaging sensor pixels during the exposure. Although this lens can be used with a close subject rendered large in the frame, lenses such as this one are often used at normal (or even long) subject distances. The resulting low magnification means those subjects' details more readily stay in their pixels, enabling the longer exposures required to compensate for a narrower aperture to still deliver sharp results, free of subject or camera motion blur.

Also, many uses for this lens require a narrow aperture, such as f/8, to keep everything in the frame sharp. Photographers concentrating on landscape, architecture, real estate, etc. may seldom use the widest aperture options in this lens.

Still, f/2.8 remains advantageous for a lens in this class. Those photographing moving subjects, such as at sports and indoor events, or under the night sky where light levels are so low that the earth's rotation becomes a source of camera motion, usually prefer a wide aperture lens to the increased ISO setting alternatively required.

It is hard to diffusely blur the background with the low magnification provided by an ultra-wide-angle lens. Such lenses render the background details small, keeping the background subjects more recognizable (and potentially distracting). Still, this lens's short minimum focus distance can create a relatively strong blur.

These examples illustrate the maximum blur this lens can create:

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Do you ever intentionally shoot blurred images? I love this artistic look that also serves well as a background image.

Most will appreciate this lens's constant max aperture, enabling f/2.8 throughout the focal length range.

Image Stabilization

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The Tamron 11-20mm F/2.8 Di III-A RXD Lens does not feature vibration compensation. Omitting the VC system reduces the size, weight, complexity, and cost. However, optical stabilization is a useful feature.

Sony addresses that omission with Steady Shot IBIS (In-Body Image Stabilization) in their Alpha cameras. In addition to reducing camera shake, the stabilized imaging sensor provides a still viewfinder image, enabling careful composition. Furthermore, sensor-based AF takes advantage of the stabilized view for improved accuracy.

With no IS switch on the lens, the camera menu must be used to enable or disable IBIS or check the current settings. This extra step is a slight impediment to working quickly, going from tripod mounted to handholding, for example.

Image Quality

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This lens has a wide aperture, and the wide-open image quality it delivers makes you want to use it.

This lens is sharp in the center of the frame from 11mm through 20mm. Remember that the 11mm barrel distortion will enlarge the center-of-the-frame details considerably more than the modest pincushion distortion at 20mm, creating an illusion of sharper performance at 11mm in the central resolution lines. Some of the other chart features, such as the numbers, provide more accurate comparisons of this lens's various focal lengths in this case.

Stopping down the aperture produces little image center sharpness improvement, and fortunately, none is needed.

Lenses typically show decreased sharpness in the periphery of the image circle, where light rays are refracted to a stronger angle than in the center. This one shows only a slight decline from the center to the corner. While f/4 produces a modest corner sharpness improvement, the clearing of the peripheral shading has the biggest impact.

The resolution chart is brutal/merciless on image quality, so let's take the testing outdoors, next looking at a series of center-of-the-frame 100% resolution crop examples. These images were captured in RAW format using a Sony Alpha 1 and processed in Capture One using the Natural Clarity method. The sharpening amount was set to only "30" on a 0-1000 scale. Note that images from most cameras require some level of sharpening, but too-high sharpness settings are destructive to image details and hide the deficiencies of a lens.

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All of these tests, along with many others, were captured through f/8. However, the f/2.8 image quality is great, and the other results appeared superfluous, not worth your time to review.

Next, we'll look at a series of comparisons showing 100% resolution extreme top left corner crops captured and processed identically to the above center-of-the-frame images. The lens was manually focused in the corner of the frame to capture these images.

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Samples taken from the outer extreme of the image circle show a lens's worst performance, and this lens's worst performance is quite good. Study the upper left details in each sample to form your opinion. Again, the primary advantage of the f/4 results is the clearing of the vignetting increasing contrast.

Corner sharpness does not always matter, but it sometimes does, including when photographing landscapes and architecture, and this lens is ready for those uses.

The Tamron 11-20 does not exhibit focus shift, the plane of sharp focus moving forward or backward as the aperture is narrowed (residual spherical aberration or RSA).

When used on a camera that utilizes its full image circle, a lens is expected to show peripheral shading at the widest aperture settings, and as mentioned, this lens has that. The just under 3 stops of shading in the 11mm corners is noticeable. Shading quickly diminishes with focal length increase, with just over 2 stops showing in the 14mm corners and slightly less at longer focal lengths.

Want less corner shading? Stopping down is the near-universal solution. F/4 reduces 11mm corner shading by about a full stop to 2 stops, though longer focal lengths see only modest improvement to just under 2 stops. Only slight shading improvements are realized at f/5.6 and narrower apertures, with over a stop to a stop and a half present at f/11.

One-stop of shading is often considered the number of visibility, though subject details provide a widely varying amount of vignetting discernibility. Vignetting is correctable during post-processing with increased noise in the brightened areas the penalty, or it can be embraced, using the effect to draw the viewer's eye to the center of the frame. Study the pattern shown in our vignetting test tool to determine how your images will be affected.

Lateral (or transverse) CA (Chromatic Aberration) refers to the unequal magnification of all colors in the spectrum. Lateral CA shows as color fringing along lines of strong contrast running tangential (meridional, right angles to radii), with the mid and especially the periphery of the image circle showing the most significant amount as this is where the most significant difference in the magnification of wavelengths typically exists.

With the right lens profile and software, lateral CA is often easily correctable (often in the camera) by radially shifting the colors to coincide. However, it is always better to avoid this aberration in the first place.

Color misalignment can be seen in the site's image quality tool, but let's also look at a set of worst-case examples. The images below are 100% crops from the extreme top left corner of Sony a1 frames showing diagonal black and white lines.

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Only black and white colors should be present in these images, with the additional colors indicating the presence of lateral CA. The color separation is strong at the wide end and still moderate at 20mm.

A relatively common lens aberration is axial (longitudinal, bokeh) CA, which causes non-coinciding focal planes of the various wavelengths of light. More simply, different colors of light are focused to different depths. Spherical aberration, along with spherochromatism, or a change in the amount of spherical aberration with respect to color (looks quite similar to axial chromatic aberration but is hazier) are other common lens aberrations to observe. Axial CA remains somewhat persistent when stopping down, with the color misalignment effect increasing with defocusing. The spherical aberration color halo shows little size change as the lens is defocused, and stopping down one to two stops generally removes this aberration.

In the real world, lens defects do not exist in isolation, with spherical aberration and spherochromatism generally found, at least to some degree, along with axial CA. These combine to create a less sharp, hazy-appearing image quality at the widest apertures.

The examples below compare the fringing colors of the defocused specular highlights in the foreground to the background. The lens has introduced any differences from the neutrally colored subjects.

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These results are good. The foregrounds and backgrounds show little color-fringing difference.

Bright light reflecting off lens elements' surfaces may cause flare and ghosting, resulting in reduced contrast and sometimes interesting, usually objectionable visual artifacts. The shape, intensity, and position of the flare and ghosting effects in an image are variable, dependent on the position and nature of the light source (or sources), selected aperture, shape of the aperture blades, and quantity and quality of the lens elements and their coatings. Additionally, flare and ghosting can impact AF performance.

This lens features Tamron's second-generation BBAR-G2 Coating, a "groundbreaking advancement", to combat flare and ghosting. It is easy to get the sun in the frame when using ultra-wide-angle focal lengths, and this lens produced relatively minor flare effects even at narrow apertures in our standard sun in the corner of the frame flare test.

Flare effects can be embraced or avoided, or removal can be attempted, though removal is sometimes challenging.

Two lens aberrations are particularly evident in images of stars, mainly because bright points of light against a dark background make them easier to see. Coma occurs when light rays from a point of light spread out from that point instead of being refocused as a point on the sensor. Coma is absent in the center of the frame, gets worse toward the edges/corners, and generally appears as a comet-like or triangular tail of light that can be oriented either away from the center of the frame (external coma) or toward the center of the frame (internal coma). The coma clears as the aperture is narrowed. Astigmatism is seen as points of light spreading into a line, either sagittal (radiating from the center of the image) or meridional (tangential, perpendicular to sagittal). This aberration can produce stars appearing to have wings. Remember that Lateral CA is another aberration apparent in the corners.

The images below are 100% crops taken from the top-left corner of Sony a1 images captured at the widest available aperture.

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The 11 and 16mm results are good, but star stretching is apparent in the 20mm results.

This lens has moderate barrel distortion at the wide end that rapidly becomes negligible at around 13 or 14mm. Pincushion distortion then sets in and becomes moderately strong by 18mm.

As seen earlier in the review, it is easy to illustrate the strongest blur a lens can create, and wide-angle lenses are inherently disadvantaged in this regard. Due to the infinite number of variables present among available scenes, assessing the blur quality, bokeh, is considerably more challenging. Here are f/11 (for diaphragm blade interaction) 100$ crop examples.

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The first example shows smoothly filled defocused highlights, but the 7 aperture blades turn the circle into a polygon (a heptagon) when stopped down this much. The outdoor foliage results appear nice, normal.

Except for a small number of specialty lenses, the wide aperture bokeh in the frame's corner does not show round defocused highlights, instead showing cat's eye shapes due to a form of mechanical vignetting. If you look through a tube at an angle, similar to the light reaching the frame's corner, the shape is not round. That is the shape we're looking at here.

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Only minor truncation shows in this lens's corners.

A 7-blade count diaphragm will create 14-point sunstars (diffraction spikes) from point light sources captured with a narrow aperture. Generally, the more a lens diaphragm is stopped down, the larger and better shaped the sunstars tend to be. Wide aperture lenses tend to have an advantage in this regard, and this lens can produce beautiful stars, as illustrated below.

The example above was captured at 16mm f/16. 11mm sunstars appear similar but less magnified, and a slight flaring of the spikes shows at 20mm.

The design of this lens is illustrated below.

"High resolution performance is maintained across the entire frame with the well-balanced arrangement of two GM (Glass Molded Aspherical) lens elements. Two LD (Low Dispersion) and one XLD (eXtra Low Dispersion) lens elements are used to suppress the chromatic aberrations that tend to occur when shooting at the wide-open aperture of fast-aperture lenses." [Tamron]

The Tamron 11-20mm F/2.8 Di III-A RXD Lens shows strong to moderate lateral CA, some geometric distortion at the focal length extents, and noticeable peripheral shading even at narrow apertures, but there is otherwise little to complain about. This lens produces sharp, impressive results.

Focusing

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The Tamron 11-20mm F/2.8 Di III-A RXD Lens's AF system is powered by a high precision RXD (Rapid eXtra-silent stepping Drive), suitable for stills and video.

"The AF drive on the 11-20mm F2.8 includes an RXD motor unit to help you stay focused on the action. RXD uses an actuator to precisely control the rotational angle of the motor, allowing it to directly drive the focusing lens without passing through a reduction gear. A sensor that precisely detects the position of the lens enables high-speed and accurate AF, which is ideal when shooting continually moving subjects or recording video. And with a focusing system that is both smooth and quiet, the 11-20mm F2.8 lets you shoot free from stress not worrying the drive sound in a quiet environment." [Tamron]

This lens internally locks focus nearly instantly (in AF-C mode on the Sony a1 as the de-focus then focus AF-S characteristic has an obvious lag) and nearly silently, with only a faint click heard. Low-light AF is on this lens's capabilities list, locking focus on good contrast in extremely dark scenarios.

Non-cinema lenses usually require refocusing after a focal length change. As illustrated in the 100% crops below, the reviewed lens does not exhibit parfocal-like characteristics. When focused at 20mm, zooming to the wider focal lengths results in focus blur.

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FTM (Full Time Manual) focusing is supported in Sony's DMF (Direct Manual Focus) mode with the shutter release half-pressed or the AF-ON button pressed. This lens does not have an AF/MF switch, requiring this frequently used camera setting to be changed via the menu system (or via a camera switch on some models).

Logically, a compact lens gets a small focus ring. While small, this ring is quite usable, and its location behind the raised hood makes it easy to locate tactilely. The rotation is reasonably smooth and the resistance is good.

This lens features a non-linear rate of focus change based on the ring's rotation speed. Turn the ring fast, and about 85° of rotation creates a full-extent change. When turned slowly, about 800° of rotation affects the same change at 11mm and 450° it at 20mm, where the minimum focus distance is longer.

I prefer linear MF adjustments, but Tamron implemented this variable rate system well (the annoyance level is very low).

It is normal for the scene to change size in the frame as the focus is pulled from one extent to the other. This effect is focus breathing, a change in focal length resulting from a change in focus distance. Focus breathing impacts photographers intending to use focus stacking techniques, videographers pulling focus (without movement to camouflage the effect), and anyone critically framing while adjusting focus.

This lens produces a modest change in subject size through a full-extent (worst-case) focus distance adjustment.

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This lens has a minimum focus distance of 5.9" (150mm), and at 11mm, it generates a significant 0.25x maximum magnification spec.

Model	Min Focus Distance		Max Magnification
Canon RF-S 10-18mm F4.5-6.3 IS STM Lens	5.5"	(140mm)	0.23x
Sigma 10-18mm F2.8 DC DN Contemporary Lens	4.6"	(116mm)	0.25x
Tamron 11-20mm F/2.8 Di III-A RXD Lens	5.9"	(150mm)	0.25x
Tamron 17-28mm f/2.8 Di III RXD Lens	7.5"	(190mm)	0.19x

At 11mm, a subject measuring approximately 3.0 x 2.0" (76 x 51mm) fills the imaging sensor at this lens's minimum MF distance. At 20mm, a 5.25 x 3.5" (133 x 89mm) subject does the same.

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The USPS love stamps shared above have an image area that measures 1.05 x 0.77" (26.67 x 19.558mm), and the overall individual stamp size is 1.19 x 0.91" (30.226 x 23.114mm).

This lens produces sharp center of the frame details at 11mm at the minimum focus distance with a wide-open aperture, but the image periphery is strongly blurred due to field curvature. The wide-open results at 20mm are improved, and a narrow aperture significantly improves minimum focus distance corner image quality.

The minimum focus distance is measured from the imaging sensor plane with the balance of the camera, lens, and lens hood length taking their space out of the number to create the working distance. At 20mm, there is plenty of working distance at the minimum focus distance but at 11mm, the plane of sharp focus is only about 0.7" (18mm) in front of the lens without the hood attached. Even with the broad light source used for the stamp photos, the lens significantly shaded the subject.

This lens is not compatible with Tamron, Canon, or Sony teleconverters.

Design & Features

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Tamron uses high-quality construction for its lenses, and as usual for the class, this lens features engineering plastic exterior construction.

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After the increase from the mount, the lens maintains a constant diameter aside from the ribbed rings that extend outward slightly, which makes them easy to find. The zoom ring is modest in size and smoothly turns with a comfortable resistance. The relatively short 60° of total rotation creates fast access to the full range.

This zoom lens extends with focal length decrease. At 11mm, it extends a modest 0.25" (6.3mm), and there is negligible play in the barrel even when fully extended.

This lens does not have buttons or switches. The lack of switches should mean increased reliability, including a decreased opportunity for dirt and moisture penetration, and reduced cost.

This lens design features dust and moisture resistance.

The front lens element has a fluorine coating that repels fingerprints, dust, water, oil, and other contaminants and makes cleaning considerably easier.

This compact, lightweight lens is a pleasant choice for extended carry sessions, including in the hand or in the pack.

Model	Weight oz(g)		Dimensions w/o Hood "(mm)		Filter	Year
Canon RF-S 10-18mm F4.5-6.3 IS STM Lens	5.3	(150)	2.7 x 1.8	(69.0 x 44.9)	49	2023
Sigma 10-18mm F2.8 DC DN Contemporary Lens	9.0	(255)	2.8 x 2.5	(72.0 x 64.0)	67	2023
Tamron 11-20mm F/2.8 Di III-A RXD Lens	11.8	(335)	2.9 x 3.4	(73.0 x 86.2)	67	2021
Tamron 17-28mm f/2.8 Di III RXD Lens	14.8	(420)	2.9 x 3.9	(73.0 x 99.0)	67	2019

View the complete Tamron 11-20mm F/2.8 Di III-A RXD Lens Specifications using the site's lens specifications tool for many more comparisons.

Here is a visual comparison:

Positioned above from left to right are the following lenses:

Canon RF-S 10-18mm F4.5-6.3 IS STM Lens
Sigma 10-18mm F2.8 DC DN Contemporary Lens
Tamron 11-20mm F/2.8 Di III-A RXD Lens
Tamron 17-28mm f/2.8 Di III RXD Lens

The Canon lens is considerably smaller and lighter than the rest, but it lacks the wide aperture. The Sigma lens is slightly lighter and noticeably shorter than the Tamron 11-20. The Tamron 17-28 illustrates the size difference of the full-frame equivalent lens.

The same lenses are shown below extended with their hoods in place.

Use the site's product image comparison tool to visually compare the Tamron 11-20mm F/2.8 Di III-A RXD Lens to other lenses.

Like so many other recently released lenses, including many Tamron models, the Tamron 11-20 uses 67mm threaded filters. Filters of this moderately small size are affordable, and due to their popularity, they are easy to find and efficiently shared.

A standard-thickness circular polarizer filter will increase peripheral shading. Therefore, a slim model such as the Breakthrough Photography X4 is recommended.

Tamron includes lens hoods in the box. Tamron adds an "H" prefix to the lens model number first using a particular hood. In this case, the HA046 was first featured on the Tamron 17-28mm f/2.8 Di III RXD Lens model A046.

This impact-absorbing semi-rigid plastic hood provides good protection to the front element from bright light and scratches. The mold-ribbed interior aids reflection avoidance. A push-button release to make the bayonet mount smoother was omitted.

A case is not included in the box.

Price, Value, Compatibility

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Tamron's name is synonymous with good value, and this useful lens, featuring great performance and a reasonable price, furthers that reputation.

Behind the "Di III" meaning is that this lens is designed for use on mirrorless interchangeable lens cameras. The Tamron 11-20mm F/2.8 Di III-A RXD Lens is compatible with Sony E-mount and Canon RF (coming in 2024) cameras, including full-frame and APS-C sensor format models. However, this lens only projects an APS-C image circle, which causes full-frame cameras to switch into crop mode. A Fujifilm X mount version is also available.

"This product is developed, manufactured and sold based on the specifications of E-mount which was disclosed by Sony Corporation under the license agreement with Sony Corporation." [Tamron]

Tamron USA provides a 6-year limited warranty.

The reviewed 11-20mm F/2.8 Di III-A RXD Lens was on loan from Tamron.

Alternatives

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The Sigma 10-18mm F2.8 DC DN Contemporary is the first lens I wanted to compare.

In the image quality comparison, the Tamron lens is the modestly sharper option. At 16mm and 18mm, the Sigma lens is slightly sharper in the periphery. The Sigma lens has slightly less pincushion distortion at the long end and less lateral CA. The Tamron lens creates the best sunstars.

The Tamron 11-20mm F/2.8 Di III-A RXD vs. Sigma 10-18mm F2.8 DC DN Contemporary Lens comparison shows the Sigma lens shorter and weighing 2.8 oz (80g) less. The Sigma lens's 10mm is noticeably wider than the Tamron's 11mm, and the Tamron lens has a modest advantage at the long end, 20mm vs. 18mm. Most other specs are identical or nearly so.

The Tamron's list price is considerably higher, but promotions may narrow that gap.

Use the site's tools to create additional comparisons.

Summary

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What is a good ultra-wide-angle zoom lens for an APS-C camera? The Tamron 11-20mm F/2.8 Di III-A RXD Lens is a great answer for APS-C format camera owners.

As I said at the beginning of this review, photographers usually consider a lens in this class to be their second or third most important lens. A most-used lens needs to be high-performing, deliver excellent image quality, quickly and reliably focus accurately, and be well designed and constructed. This lens checks those boxes and features a wide f/2.8 aperture over the entire focal length range, increasing its versatility into low-light conditions and subject-isolating background blur potential. The affordable price is welcomed by all.