Sigma 18-50 2.8-4.5 DC OS lens hands-on
7/28 UPDATE: For those who haven't been following, the original lens I did this test with was replaced as defective (it clearly wasn't working right some of the time). I took a few new test shots over the past weekend with the new lens and while it may just be wishful thinking on my part, I do think it's slightly better optically. The overall conclusions below still hold, as do the general design conclusions I reached, but I think my new lens is just a slightly better example than the old one even beyond simply working correctly :)
I'll post the new shots in a few days - sorry, you'll have to check back one more time.
Anyway, the original post continues below.
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I just wanted to post something quick about this, because I know a lot of people (including myself) have been waiting for this lens, and I just happened to find it here in Japan, at one particular Yodobashi Camera, available only in a Canon mount. It was right at $300 (29,800 yen).
I haven't had a chance to do any exhaustive tests so far but generally I'm really happy with it as an upgrade to my old Rebel XT kit lens.
Pros:
* Built like a tank, at least for a consumer-level lens (looks almost exactly like their 18-50 f/2.8 EX lens, minus the gold stripe)
* Image stabilization works really well
* Non-rotating front element
* No lens extension during zoom - all movement is internal
* Hypersonic motor is very quiet (though not silent, nor all that fast)
* Includes a hood
Cons:
* Actually slightly less sharp in the corners than my kit lens (though I've been told I had an exceptional copy of the old Canon 18-55 non-IS)
* Corner sharpness is noticeably lower than center sharpness
* Heavy
These were taken in my backyard and have not been retouched at all. So some of the exposures are not exactly right, white balance might be a bit off, etc. I did not want to damage the purity of the images as the lens saw them. The shots were all taken on a tripod, using a delayed exposure (completely hands-off), using AF. I also took shots using MF but didn't do any better on a consistent basis - I will say the comparisons themselves were the same (the "winner" at any given aperture did not change based on whether I used AF or MF). The Canon lens used as a comparison is the 18-55 non-IS kit lens, which might have some slight differences to the IS version beyond the obvious, but they perform similarly in the tests I've seen. But you can keep that in mind, at least.
My thoughts on what the shots show are below.
Clicking the thumbnails will take you to that image on Photobucket, where you can view them at 100% full size (just click anywhere on the image once it opens in Photobucket). I know, kind of clunky to compare shots, but that's why God invented tabbed browsing :)
Sigma @ 18mm f/5.6:
Canon @ 18mm f/5.6
Sigma @ 50mm f/5.6
Canon @ 55mm f/5.6
Sigma @ 18mm f/8
Canon @ 18mm f/8
Sigma @ 50mm f/8
Canon @ 55mm f/8
Sigma @ 18mm f/11
Canon @ 18mm f/11
Sigma @ 50mm f/11
Canon @ 55mm f/11
Sigma @ 50mm f/8
Canon @ 55mm f/8
Now, the stuff I know a lot of you guys are waiting for - a couple of wide open aperture shots. Clearly the Sigma lens is not as sharp there, but my thoughts on that after the photos.
Sigma @ 18mm f/2.8
Sigma @ 18mm f/2.8
Sigma @ 18mm f/3.5
The interesting thing is how much sharper the Sigma lens is at f/3.5 than f/2.8. It's almost like they designed the lens for 3.5 and then just widened it to give it better specs, even though the lens is obviously not happy about it. (I'm not sure if that's really possible.)
One thing I will say is that you would obviously only be using f/2.8 in low light handheld situations, which this really was not. In low light when shooting handheld, you're going to be a lot more satisfied with "acceptable sharpness", especially from a consumer level lens. With a lens that has no OS and can only open up to f/3.5, you will have a hard time shooting handheld even acceptably in low light. With this lens, the f/2.8 coupled with the OS gives you the ability to shoot in very low light without unnecessary blur from camera shake, although you will not get "tack sharp" images out of it no matter what you do at that aperture.
Sigma @ 50mm f/4.5
Compare to the similar shot above. Again, it is noticeably softer at 4.5 at this end of the zoom than at f/8 or f/11, which is really its sweet spot.
Generally I am really happy with this lens, and if you look at the overall lens market, I think Sigma did what they needed to do here. This is not an EX lens designed to compete with Sigma's own 18-50 f/2.8. It is designed more to fill a hole just above Canon's cheap 18-55mm kit lens, and it costs about $100 more. The optical quality of the two lenses is about equivalent - the Sigma may be slightly sharper in the center at certain apertures, the Canon better in the corners.
For that extra $100, though, you are getting much better build quality, an included lens hood, a non-telescoping zoom, a non-rotating front element, and (from what I've read, at least), more capable image stabilization. You're also getting a wider aperture, though whether or not that's really useful given the performance is up to you (though I know I will be happy to have it when I need it). I personally think all of that is easily worth the extra cost over the Canon lens.
The other major difference between the Canon and Sigma lenses are that the Canon seems to be at its best at f/5.6, whereas the Sigma is at its best at f/8 or f/11. A lot of people will find the Canon sweet spot to be more useful in more situations, and I don't disagree with that. It's kind of odd - and my one real criticism of the Sigma lens - that its specs suggest it is designed for low light, but it's really happiest in bright light. Still, that isn't unusual for Sigma, who often seem to design their lenses this way.
Summing up, I can highly recommend this lens given the price, but you shouldn't be expecting EX (and certainly not Canon L class!) performance. It is what it is - a better quality alternative to Canon's 18-55 IS.
