Tamron 10-24mm f/3.5-4.5 Di II LD SP AF

SLRgear Review
March 15, 2009
by Andrew Alexander

Since the advent of APS-C sized sensors for digital SLR cameras, the concept of an ultra-wide zoom had be re-imagined. In the days of 35mm film, a lens that could offer a 17mm field of view pretty much did the job; on the APS-C sensor, this is no longer an especially wide angle.

Tamron has been an early adopter of ultra-wides for sub-frame sensor cameras, first introducing the 11-18mm ƒ/4.5-5.6 and in October of 2008, the subject lens of this review, the 10-24mm ƒ/3.5-4.5. With a greater focal length range and maximum apertures, the new lens is just slightly larger and heavier - but actually has a lower price point than the 11-18mm.

On a sub-frame (APS-C) camera, the lens provides an equivalent field of view of 16-38mm (Canon) or 15-36mm (others). It will mount and operate on full-frame cameras, though hard vignetting is visible until about 15mm. This lens isn't a "constant" lens, in that as you increase the focal length, both the maximum and minimum aperture sizes decrease. The following table reflects the changes as you zoom:

The Tamron 10-24mm ƒ/3.5-4.5 zoom lens ships with a petal-shaped lens hood, takes 77mm filters, and retails for approximately $500.

Sharpness
The Tamron 10-24mm ƒ/3.5-4.5 is generally a sharp lens, with a few important caveats.

Wide-open (largest aperture) performance is very good, more so at the wider end of the zoom range; there's a large ''sweet spot'' of sharpness in the center of the frame, offset by significant corner softness. As the lens is zoomed in towards 24mm, central sharpness degrades significantly. The worst of it shows at around 18-20mm, where average sharpness is in the order of 3-4 blur units across the frame, but things improve marginally by 24mm. It's clear Tamron has optimized the lens for wide-angle usage, though - which makes sense, given its 10mm focal length capability is a prime selling point.

Stopped down, we begin to see some really good performance for sharpness. There's not much of a difference at ƒ/4 - you'd only see that at 10-13mm anyway - but by ƒ/5.6, corner softness is greatly reduced at 10mm, and overall the lens produces very sharp (~1.5 blur units) results. Other focal lengths at ƒ/5.6 are also pretty good, but over 13mm the sweet spot of central sharpness is very small, surrounded by good results of around 3 blur units. I'd say for the most consistent performance between focal lengths, you could aim at ƒ/5.6, but for wide-angle (10mm) usage you wouldn't be disappointed wide open at ƒ/3.5. Results are marginally better at ƒ/8 on the wide end, and above 15mm this is the optimal setting.

Fully stopped-down performance (ƒ/22-29) is good but unspectacular - around 3-5 blur units across the frame. Diffraction limiting begins to set in noticeably at ƒ/16.

In summary, excellent results for this lens when used at wide-angle, even wide open. Above 13mm, you need to stop down to ƒ/5.6 or even ƒ/8 to get optimal results for sharpness.

Chromatic Aberration
Chromatic aberration is fairly well-controlled in this lens, in the central portion of the frame; in the corners, where barrel distortion sets in noticeably, the lens is fairly helpless and our test results show very high amounts of CA. CA can be reduced slightly at 10mm by stopping down to ƒ/8; at 13mm and above, you actually get better CA tolerance by shooting at wider apertures.

Shading (''Vignetting'')
Below 15mm, there is always some form of corner shading, which isn't surprising for such a wide-angle lens.

At 10mm at ƒ/3.5, the corners are a full stop darker than the center. Stopping down alleviates light falloff - by ƒ/5.6 and smaller, you're looking at a differential of around 2/3 EV. 13-15mm show similar performance of between 1/2 and 2/3 EV of corner shading, and the best results can be obtained by using a focal length of 18mm or greater. At these focal lengths, light falloff is 1/3EV or less.

Distortion
Barrel distortion is typical in wide-angle lenses, but the 10-24mm Tamron controls it quite well throughout the frame. In the extreme corners distortion is quite high - in the order of +1.0% at 10mm - but this reduces to 0.5% at 24mm. Average performance (distortion in the central region of the frame) is quite good, at a constant 0.25%.

Autofocus Operation
Tamron uses an electrical in-lens motor for the 10-24mm, moving a mechanical focusing system, which is comparatively slow and noisy. It takes about 1.25 seconds to focus completely from close-focus to infinity and back, but it does seem slightly faster when performing shorter-range focusing operations. The front lens element doesn't rotate during autofocus, but the focusing ring does, so keep your fingers clear.

Macro
The 10-24mm offers a magnification rating of 0.20x (1:5.1), but you're still better off using a more dedicated macro lens owing to the significant barrel distortion. The minimum close-focusing distance is 24cm (just over 9 inches).

Build Quality and Handling
The Tamron 10-24mm is finished in a textured matte black with an economy of features. It's small and light, owing to its plastic construction, but there is no flexing or rattling to be found. It uses a metal lens mount, and plastic filter 77mm threads. The only control element on the lens other than zoom and focus rings is a single switch to override focus operations.

The lens is equipped with an marked distance scale, measured in feet and meters. There is no depth of field scale - not that it would be of much use on an ultrawide lens - nor is there an infrared index marker.

The zoom ring is nicely cammed, offering just the right amount of resistance while being turned. The ring itself is rubber, about an inch wide with segmented ribs, and is found closer to the lens mount. Zoom creep isn't an issue with this lens, and even if it was, the lens only extends by 1/2'' at the 24mm end of its focal length spectrum. The zoom ring requires about 75 degrees of turning action to go through the entire focal range.

As noted previously, the focus ring turns during autofocus operations. There is plenty of play in the manual focus ring - part of the reason the autofocus is so slow - it takes about ninety degrees of turning action to go through the focus range. The focus action has hard stops at both ends of its range, and will focus slightly past infinity. The ring is rubber, about 1/2'' wide, with a ribbed texture.

The lens ships with a petal-shaped lens hood, which attaches with a bayonet mount and reverses on the lens for storage. When mounted, the hood adds 1 1/2'' to the overall length of the lens. The interior of the hood is ribbed, but as is the case for wide-angle lenses, offers very little lens shading when used at wide angles.

As is the case with most wide-angle lenses, using the pop-up flash will produce a shadow on the lower portion of the image.

Alternatives

While each of the major manufacturers offers an ultrawide zoom for sub-frame cameras, we'll examine some alternatives on the logic that you're looking at the Tamron 10-24mm because you're looking for something that's not the same brand as your camera.

Tamron 11-18mm ƒ/4.5-5.6 Di II LD Aspherical IF SP AF ~$550
The original ultra-wide zoom produced by Tamron is still a very capable optic, as sharp as the 10-24mm (if not sharper, in some cases). CA is controlled well, if not better than the 10-24mm (especially at wider angles), distortion is less severe as is light falloff. Both take 77mm filters.

Tokina 12-24mm ƒ/4 AT-X 124 AF PRO DX II ~$580
The Tokina doesn't go as wide as the Tamron, but offers a constant aperture of ƒ/4 throughout its range. We haven't tested the version 2 of this lens, but we found version I to be impressively sharp - at least, until you hit 24mm. CA is well-controlled, corner shading is marginal, and distortion is pretty good, too - by 24mm, there's no barrel distortion. However, the lens is only available in Canon and Nikon mounts.

Sigma 10-20mm ƒ/4-5.6 EX DC HSM ~$450
Sigma's ultrawide offers some of the best performance for the dollar. Tamron's 10-24mm has a bit more reach on the tele end, but the Sigma lens is much sharper, and as it is a rectilinear design, offers better distortion and less corner softness. It is especially resistant to chromatic aberration (above 10mm), and with its HSM motor, is much quieter to focus. Finally, it's less expensive. Sigma's also announced a constant ƒ/3.5-aperture version of this lens.

Conclusion
There's no denying that with a focal range of 10-24mm, the Tamron lens is the current champ of ultra-wide range (the Canon 10-22mm comes in second). Its optical performance is very good: nice and sharp at 10mm, except in the extreme corners and good tolerance to CA (again, except in the corners). Distortion is a little high - fairly typical for wide-angle lenses - and corner shading is a bit high, as well. Both of these can be solved in post-processing, though.

With a price point lower than its existing ultrawide 11-18mm, the Tamron 10-24mm is an attractive proposition, offering good performance and exceptional value in the same package.

Sample Photos

The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.

Still Life shot

VFA target

As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.