Conclusion - Pros
Extremely good optics
Highly effective image stabilization
Silent, accurate focusing
Impressive flare resistance
Very good build quality including sealing
Competitive price compared to camera manufacturers' equivalents
Conclusion - Cons
Unpleasant vignetting at F2.8 on full frame at the telephoto end
Slightly less-fast autofocus than Canon or Nikon equivalents (but far from slow)
AF and VC switches rather stiff, difficult to change quickly
Overall conclusion
The Tamron SP 24-70mm F/2.8 Di VC USD is distinguished by being the first fast standard zoom for full frame cameras to include optical image stabilization. The fact that it does so in a design that includes a ring-type ultrasonic motor for fast, silent autofocus and a degree of weathersealing (Tamron uses the term 'drip-proof'), all at a significantly lower price than Canon's non-stabilized EF 24-70mm f/2.8L II USM that was announced around the same time, might lead you to think suspect must be some serious compromise involved in its design. But there isn't.
The Tamron's test results are very good indeed, making it a very real competitor to the 24-70mm F2.8s from Canon, Nikon and Sony. About the only criticism is fairly strong barrel distortion at wideangle on full frame, but this is easy to correct in this day and age when necessary. As usual for a full frame lens you can also expect noticeable vignetting when shooting wide open at either end of the zoom range, which in some circumstances can be quite unattractive. But again it's pretty straightforward to correct when necessary.
Once we get outside the studio and start using the lens for real, it continues to perform well. Autofocus is silent and accurate - it's not quite as quick as the Canon equivalent when tested side-by-side on the same camera bodies, but for most purposes it should be easily fast enough. It also behave well with regards to the less-quantifiable aspects of image quality - it works well when shooting into the light, and generally gives attractively-blurred out-of-focus backgrounds.
Obviously the lens's standout feature is its optical image stabilization, and crucially it works very well. In our controlled testing it allows you to get usably-sharp images at shutter speeds up to four stops slower than you can with it turned off, which is up there with the best we've tested. Again this is reflected in real-world shooting, where you can hand-hold the lens with much slower shutter speeds and still get sharp results. This is extremely useful not just in low light, but also if you want to stop down for depth of field, or use slow shutter speeds for creative blur effects.
We don't have any complaints about the build quality either - the 24-70mm feels much better constructed than Tamron's consumer lenses. Some users many not take kindly to the front-mounted zoom ring - most lenses of this type or size place the manual focus ring at the front, with the zoom ring closer to the camera towards the center of gravity of the combination - but we suspect this might only be any kind of problem in practice if you'll be regularly swapping lenses with a wideangle zoom that has a conventional layout. One criticism we do have though (and it's a small one) is that the rather flat profile and stiff action of the AF and VC switches can make it tricky to change these settings in a hurry.
The Final Word
Overall, we're extremely impressed with the Tamron 24-70mm F/2.8 VC. It demonstrates that it's entirely possible to add an effective image stabilization system to a lens of this type without a significant drop in quality elsewhere. The optics are excellent, the autofocus fast, silent and accurate, and the build quality very good indeed.
Overall the Tamron comes so close to the much more expensive non-stabilized Canon and Nikon lenses, both optically and operationally, that it's difficult to see why most enthusiast photographers might choose to buy them instead. That's not to say that there aren't any differences - the Tamron's not quite so quick at focusing, and chances are it's not as well weathersealed - but quite simply it offers much better value for your money.
Conclusion - Pros
Extremely good optics
Highly effective image stabilization
Silent, accurate focusing
Impressive flare resistance
Very good build quality including sealing
Competitive price compared to camera manufacturers' equivalents
Conclusion - Cons
Unpleasant vignetting at F2.8 on full frame at the telephoto end
Slightly less-fast autofocus than Canon or Nikon equivalents (but far from slow)
AF and VC switches rather stiff, difficult to change quickly
Overall conclusion
The Tamron SP 24-70mm F/2.8 Di VC USD is distinguished by being the first fast standard zoom for full frame cameras to include optical image stabilization. The fact that it does so in a design that includes a ring-type ultrasonic motor for fast, silent autofocus and a degree of weathersealing (Tamron uses the term 'drip-proof'), all at a significantly lower price than Canon's non-stabilized EF 24-70mm f/2.8L II USM that was announced around the same time, might lead you to think suspect must be some serious compromise involved in its design. But there isn't.
The Tamron's test results are very good indeed, making it a very real competitor to the 24-70mm F2.8s from Canon, Nikon and Sony. About the only criticism is fairly strong barrel distortion at wideangle on full frame, but this is easy to correct in this day and age when necessary. As usual for a full frame lens you can also expect noticeable vignetting when shooting wide open at either end of the zoom range, which in some circumstances can be quite unattractive. But again it's pretty straightforward to correct when necessary.
Once we get outside the studio and start using the lens for real, it continues to perform well. Autofocus is silent and accurate - it's not quite as quick as the Canon equivalent when tested side-by-side on the same camera bodies, but for most purposes it should be easily fast enough. It also behave well with regards to the less-quantifiable aspects of image quality - it works well when shooting into the light, and generally gives attractively-blurred out-of-focus backgrounds.
Obviously the lens's standout feature is its optical image stabilization, and crucially it works very well. In our controlled testing it allows you to get usably-sharp images at shutter speeds up to four stops slower than you can with it turned off, which is up there with the best we've tested. Again this is reflected in real-world shooting, where you can hand-hold the lens with much slower shutter speeds and still get sharp results. This is extremely useful not just in low light, but also if you want to stop down for depth of field, or use slow shutter speeds for creative blur effects.
We don't have any complaints about the build quality either - the 24-70mm feels much better constructed than Tamron's consumer lenses. Some users many not take kindly to the front-mounted zoom ring - most lenses of this type or size place the manual focus ring at the front, with the zoom ring closer to the camera towards the center of gravity of the combination - but we suspect this might only be any kind of problem in practice if you'll be regularly swapping lenses with a wideangle zoom that has a conventional layout. One criticism we do have though (and it's a small one) is that the rather flat profile and stiff action of the AF and VC switches can make it tricky to change these settings in a hurry.
The Final Word
Overall, we're extremely impressed with the Tamron 24-70mm F/2.8 VC. It demonstrates that it's entirely possible to add an effective image stabilization system to a lens of this type without a significant drop in quality elsewhere. The optics are excellent, the autofocus fast, silent and accurate, and the build quality very good indeed.
Overall the Tamron comes so close to the much more expensive non-stabilized Canon and Nikon lenses, both optically and operationally, that it's difficult to see why most enthusiast photographers might choose to buy them instead. That's not to say that there aren't any differences - the Tamron's not quite so quick at focusing, and chances are it's not as well weathersealed - but quite simply it offers much better value for your money.
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