Tamron 28-75mm f/2.8 XR Di LD Aspherical IF SP AF

Name: Tamron 28-75mm f/2.8 XR Di LD Aspherical IF SP AF
Brand: Tamron
Rating: 8.2 (42 reviews)

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Lens Reviews / Tamron Lenses i Lab tested

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Lens Review
Specifications

28-75mm	$485 average price

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Chromatic Aberration
Vignetting
Geometric Distortion

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Chromatic Aberration
Vignetting
Geometric Distortion

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Pentax K - Black
Sony A-mount - Black

(From Tamron lens literature) The most compact and lightest in the history of fast zoom lenses. Thanks to the revolutionary downsizing "XR" technology employed by Tamron in the development of high-power zoom lenses such as the 28-200mm and 28-300mm, the dramatic compactness that makes this lens the world's smallest and lightest is achieved. Its compactness makes it look and feel like an ordinary standard zoom lens, yet the versatility that a fast constant maximum aperture offers will definitely reshape your photographic horizons.

Note: On May 15, 2008, Tamron announced a Nikon version (model A09NII) will be available with a built-in AF motor for use with all Nikon DSLRs including the D40, D40x and D60.

Test Notes

The Tamron 28-75mm f/2.8 lens is a contemporary of a design produced by every other major lens manufacturer. The zoom range would qualify it as a wide angle to short telephoto on a film body, but on a digital body with an APS-C size sensor, the focal range is an equivalent 42-113mm ( 1.5x) or 45-120mm (1.6x). It's arguable whether this focal range has been supplanted by a newer crop of so-called digital lenses, optimized for the smaller sensor size: however, the remaining asset for this category of lens is its constant f/2.8 aperture, useful in low-light situations and portraiture where a thin depth of field is required. As well, it's a traditional full-frame lens, usable on full-frame film and digital cameras. As a third-party lens maker, Tamron provides this lens offering in four major mounts: Canon, Minolta (Sony), Nikon, and Pentax, at a much lower price than the competition in all four. The question is, are you better off spending the extra dollars for one of the manufacturers' lenses, or does the budget lens prove itself an excellent value for the money?

Sharpness
Given that one of the most marketable features of this lens is its constant f/2.8 aperture, this will no doubt be the most popular aperture employed by shooters using this lens. Thus, an important question is, how does the lens perform when shooting wide open?

On a digital body with a sub-frame sensor, the sensor is using the central "sweet spot" of the lens: Thanks in part to this, the lens exhibits excellent sharpness with slightly soft spots in the corners on the wider side (28-35mm) at f/2.8. Zoomed out further, the sharpness deteriorates but still maintains a level that's quite acceptable. Reducing the aperture just one stop to f/4, however, produces incredible across-the-frame sharpness all the way from 28-75mm: if you demand optical excellence, then this is the optimal aperture for this lens. The lens is very well-behaved to f/11, exhibiting excellent sharpness across the frame, but diffraction begins to set in around f/16 where images become less sharp, but not unreasonably soft either.

These results change on a full-frame body. Corner softness at f/2.8 is very pronounced at all focal lengths, while still being remarkably sharp in the middle (no surprises here, as that's what we saw on the sub-frame results). Again, stop down to f/4 and these sharpness issues become almost negligible, and by f/5.6 the lens is again very well-behaved across the frame, showing excellent sharpness. When diffraction sets in around f/16, the story remains the same as we saw with the cropped sensor: not unreasonably soft, but not overly sharp either.

So you do see excellent performance, but the best results only come when you stop down to f/4, if not f/5.6; at f/2.8, you will encounter some corner softness, especially when shooting full-frame.

Chromatic Aberration
The Tamron 28-75 handles chromatic aberration very well, its optimal performance exhibited at 60mm with an aperture of f/4. CA tends to be most apparent in wide- or superwide-angle lenses, and with a wide focal length of 28mm, CA is never too much of an issue here. Points where CA occur most are with the lens wide open at f/2.8, at the widest and longest ends, but even there, it is very well controlled and shows up only in the corners of the frame. Happily, the CA performance on a full-frame body is very similar.

Shading ("Vignetting")
Looking at the test results for the APS-C sized sensor, corner shading is almost non-existent with this lens, with the worst-case scenario being wide open (f/2.8) at 75mm; even there, the light falloff in the corners is only one-quarter of an EV. However, the story changes when the lens is used on a film or full-frame sensor body, where it vignettes to some extent across the board, at all focal lengths and apertures, but most evidently at apertures wider than f/5.6. Wide open at f/2.8 at 28mm, the corners are over a full stop darker than the center of the frame (1 1/4 EV). The best performance on full-frame appears to be at 50mm from f/2.8-f/5.6, and at f/8 and smaller vignetting turns into a non-issue at the telephoto end. Fortunately, all of these problems are relatively easy to compensate for in Photoshop.

Distortion
In most zoom lenses, we see barrel distortion at the wide end, changing to pincushion at longer focal lengths, and the Tamron lens is no exception here. On the APS-C sized sensor, distortion is only truly evident on the wide end (28mm), where it reaches it maximum value of 0.5% barrel in the corners. Fully zoomed out to 75mm, there is very little pincushion distortion. These results are somewhat exacerbated on a full-frame sensor, where at the widest (28mm) the distortion increases to about 0.6% barrel, and you begin to see some pincushion distortion in the corners when zoomed out, to a maximum of 0.5%. Depending on your subject, you might not even notice these elements of distortion, and they are correctable to some degree in Photoshop.

AF Operation
The Tamron 28-75mm f/2.8 is mechanically driven, so it's not going to be as fast as newer offerings that use ultrasonic motors. That said, we found it to be quicker than we expected, and quite snappy when changing between close focus points. Racking through the full focus range is comparatively slow and there's a pause at the far extension: perhaps one second in total (though the pause could legitimately be the Canon AF system we were testing this lens on, and not the lens itself). It is not possible to override the autofocus at any point by turning the focus ring while in AF mode: you can, but you are working against the clutch, which is probably not healthy for the lens gearing. There is an MF setting which releases the clutch, and easy manual focusing is possible. There is perhaps an inch of travel in the focus ring, more than some cheaper lenses, which gives sufficient travel for accurate manual focusing. The autofocus itself is slightly noisy, but still relatively discreet. As described earlier the lens filter mount doesn't turn or extend at all while focussing.

Macro
Tamron claims that with its close-focus range of thirteen inches (33mm), it is the best in its class for this particular specification; and indeed, comparing the specifications across comparable lenses, this does indeed appear to be the case the case. There are better lenses devoted strictly to macro work, but with its maximum magnification of 1: 3.9 at 75mm it does a respectable job of macro reproduction.

Build Quality and Handling
The lens is built with the bigger zoom ring closer to the camera body, and a smaller focus ring at the far end. Both are textured well with a good grip. The lens is "assembled in China" and has a definite plastic feel: One has a definite sense that as little metal has been used as possible to make the lens lighter and less expensive. The lens comes with a substantial petal lens hood, and while attaching the hood to the lens, we noted some flex in the lens barrel. When taking some test shots from a Canon 30D with the built-in speedlight, on the wide (28mm) end you will see a shadow from the lens hood on the bottom third of the frame: you want to use an external flash for shots in this situation, or remove the hood.

There's no aperture ring, so you'll need a newer body which controls aperture from the body, and a mechanical focus drive to enable autofocus. (This leaves out cameras like the Nikon D40 and D40x, which lack an AF drive motor.) There's a lock to prevent zoom creep, but waving the lens around, we didn't experience any; perhaps in time when the mechanism is a bit more worked out, zoom creep would become a factor. Regarding the lens caps: Both are quite solid, the front being a pinch-style which goes on easily and works well. The rear is finicky about getting attached but once it's on, it stays on. Some readers remarked that the focus ring of this lens rotates during AF operation. This is true, so be aware of this fact if you're likely to be bothered by it. In our own use, it didn't bother us, as we generally didn't grip the lens towards the end of its barrel where the focus ring is located.

Alternatives

There could be a lengthy discussion concerning alternatives to this particular class of lens, not just with other lens manufacturers, but with other classes of lenses: With the advent of the digital (APS-C sized) sensor, digital lenses have now become popular to replicate the zoom ranges of traditional lenses, such as the 28-70mm range. It's arguable that the 28-75mm lens range has lost its prominence, being subordinated by zooms starting at 18mm to regain the wide-angle capability that's been lost due to the "crop factor" of the most common digital sensors. To reduce this level of complication we'll compare only lenses with a constant f/2.8 aperture. This is made a little difficult by the fact that we've only tested one other lens in the same category as of this writing, so we can really only make objective comparisons for that one, the Canon 24-70mm f/2.8L USM.

Canon EF 24-70mm f/2.8L USM ~$1,150
As if to raise a few eyebrows, the Tamron lens is actually a hair sharper than the Canon competition, across all apertures and focal lengths. While the Tamron achieves stable sharpness across its focal lengths by f/4, it's only at f/5.6 that Canon is uniformly sharp. Both lenses do fairly well with chromatic aberration, though it's much more noticeable on the Canon on the wide end. This can perhaps be expected, as the Canon goes a little wider (24mm). The Canon controls vignetting much more reliably than the Tamron though, and distortion is similar between both models. So optically it's a mixed bag, but for fit and finish it becomes quite clear that you get what you pay for: The Canon is almost twice as heavy and much more robust, and its autofocus is exceptionally quick.

Konica Minolta 28-70mm f/2.8 G AF $?
If you're using a Sony Alpha, this is your default lens in this range if you want to stay true to the brand (inasmuch as you can); otherwise, the Tamron is available in this lens mount. You're not likely to find a new version on dealer's shelves, however. When it retailed, the KM model was more than twice the price, and is about fifty percent heavier.

Nikon 24-70mm f/2.8 IF-ED AF-S ~$1699.95
Nikon 28-70mm f/2.8 IF-ED AF-S ~$1530
Renowned for its sharpness, but similarly to the Canon model, the Nikon 28-70mm is almost three times the price and almost twice the weight. For a few dollars more though, you might want to get the new 24-70mm, which is 35 grams lighter ( 1.2 oz) than its older brother, and is one of the crop of new lenses that Nikon announced in August 2007, calling particular attention to their designed-for-digital optical quality.

Pentax 28-70mm f/2.8 SMC P-FA ~$?
The Pentax offering in this lens category, similar to those of other major manufacturers, is about fifty percent heavier than the Tamron. It was also more than twice as expensive, if/when you can find it on the shelves.

Sigma 24-70mm f/2.8 EX DG Macro ~$400
Sigma 28-70mm f/2.8 EX DG ~$310
Sigma has two lenses in this particular range available for about the same price and weight as the Tamron. Again, we haven't tested either yet, but readers give the 24-70mm good marks for build quality, image quality, and bokeh (rendering of out-of-focus elements in the scene), but readers were divided over its wide-open sharpness. The average user rating was 8.14 out of 10 points. Only one reader had reviewed the 28-70mm as of this writing. He liked it well enough, but was disappointed with the softness at f/2.8. (He still felt it was a worthwhile value though, given its low price, giving it 7 points out of a possible 10.)

Tokina 28-70mm AT-X 287 AF PRO SV ~$?
At 719 grams, the Tokina is slightly heavier than the Tamron. Unfortunately, you're not likely to find it on many dealer's shelves. When you can, it should be slightly less expensive. We've not tested the Tokina ourselves; the one reader who's reviewed it reported softness at f/2.8, but gave it 8 out of 10 points overall.

Conclusion

Without detailed test results for the majority of competing offerings by major manufacturera, it's hard to make a definitive conclusion on the worthiness of this lens. However, we can say this: for the money, the lens has excellent optical qualities that rival at least one major (and much more expensive) lens in its category (the Canon 24-70mm f/2.8). The real question may be the longevity and fitness of the lens. Being made of mostly plastic, it will be a delight to carry for long stretches, but who knows how it might fair from a bit of knocking around. (In fairness, while a number of readers remarked on its plasticky feel, none reported reliability problems with it.) If you're a pro, you may already know you need a pro lens that can take it; if you're not as worried about where you may take it, then you may find yourself very pleasantly surprised by the performance of this lens, and pleased by the extra cash in your pocket.

Sample Photos!
Beginning in July 2007, we now provide sample photos of two laboratory test targets to help in our readers' evaluation of the lenses we test. 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.

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 f/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.

To see the sample shots from this lens captured with this lens on our test body, just click on either of the thumbnails below, and scroll as needed in the window that appears.

Still Life shot

VFA target

Full-Frame Test Notes:

Sharpness

On a sub-frame sensor, sharpness was excellent; these results change on a full-frame body. Corner softness at f/2.8 is very pronounced at all focal lengths, while still being remarkably sharp in the middle (no surprises here, as that's what we saw on the sub-frame results). Again, stop down to f/4 and these sharpness issues become almost negligible, and by f/5.6 the lens is again very well-behaved across the frame, showing excellent sharpness. When diffraction sets in around f/16, the story remains the same as we saw with the cropped sensor: not unreasonably soft, but not overly sharp either.

Shading ("Vignetting")
Corner sharpness wasn't much of an issue on a sub-frame sensor. However, the story changes when the lens is used on a film or full-frame sensor body, where it vignettes to some extent across the board, at all focal lengths and apertures, but most evidently at apertures wider than f/5.6. Wide open at f/2.8 at 28mm, the corners are over a full stop darker than the center of the frame (1 1/4 EV). The best performance on full-frame appears to be at 50mm from f/2.8-f/5.6, and at f/8 and smaller vignetting turns into a non-issue at the telephoto end. Fortunately, all of these problems are relatively easy to compensate for in Photoshop.