8 out of 10 points and recommendedSolid build, great range, handles flair/ghosting well.Not very sharp. Bokeh is only so-so.
I like the way Sigma builds its EX (for extra expensive) lenses and this model is as good as the other two EX lenses I own. It can take 82mm filters and one can use the lens cap even when the butterfly hood is in place.reviewed July 16th, 2009 (purchased for $650)
I need top-quality glass for my work but I'm willing to compromise for $$$ savings when I can. I have a Tamron 17-50mm 1:2.8 which is incredibly sharp - a great buy. (It is tested here at SLRGear.) I compared it to this lens, both set to 17mm under very controlled conditions. (First I tested the new Sigma for focusing accuracy. It was short by just a small bit. I made the adjustment in my Nikon D300.)
In overall impression the Sigma is comparable to the Tamron, a bit warmer but with similar contrast. Distortion at 17mm is much less than the Tamron's, but of course gets quite extreme as you near 10mm. In resolution there were large differences. At 17mm, both center and corners, the Tamron outperformed the Sigma for sharpness by a very noticeable margin with fast apertures. The gap starts closing around f/11 and the two lenses are roughly equal by f/22.
The Sigma's bokeh is a bit rough. Specular highlights aren't quite round, have some striations and halo, and are not smoothly monochromatic. None of these shortcomings is a killer, I'm just a perfectionist.
If you'll never print larger than 8x10" this lens might be ideal for you, but it is not truly up to professional caliber. However, neither are any of the other ultrawide zooms, it seems. The exceptions cost two or three times as much and don't go nearly as wide.
9 out of 10 points and recommendedValue of optics vs. price as good as it gets.Plastic
I have tested this lens extensively against above-average primes and zooms. It pretty much matches (or exceeds) the quality of each of them where they are best. Where they fall down, the Tamron beats them handily. No real weak spots in the optics. Construction quality accounts for the low cost. I'm used to much better so give this a six; lens shade attachment ring is loose; inner barrel can be tilted vs. outer.reviewed October 24th, 2009 (purchased for $420)
In its range, the only reasons to go for a better model like the Canon or Nikon are to show off how affluent you are or because you absolutely need the very best IQ.
They've come out with a new model that has VR. I assume the optics haven't changed. Why fix what ain't broken? I'm looking forward to seeing SLRGear's lens test results on it.