Canon EF-S 17-55/2.8 IS USM and Sigma 17-50/2.8 EX DC OS HSM Review

Conclusions

So after all the testing and comparing, which is the better lens? Which one would I buy?

Well, it's a difficult question. Optically there's not a huge amount of difference and neither lens has the advantage at all focal lengths, so optically it's pretty much a wash. If both lenses were the same price, came with the same accessories and had the same warranty, then I'd buy the Canon EF-S 17-55/2.8 IS USM for the following reasons:

• The Canon has slightly larger zoom range (55mm vs. 50mm)
• The Canon has Full Time Manual Focus
• The Canon focus ring doesn't rotate when focusing
• The Canon lens should have 100% compatibility with all past, present and future EOS DSLRs
• The Canon may have slightly better IS (?)

Of course the two lenses are not the same price, nor do they come with the same accessories and warranty. The Sigma 17-50/2.8 EX DC OS HSM has the following advantages:

• A price of $670 vs. $1050. That's a saving of around $380 or 33% on the Sigma lens.
• The Sigma comes with a lens hood ($45 extra for the Canon lens)
• The Sigma comes with a soft case
• The Sigma comes with 4 years total warranty vs. 1 year on the Canon

The potential downside on the Sigma are questions of reliability and compatibility. In the past Sigma lenses have had problems with EOS DSLRs released after the lens. If the lens has still been in production, Sigma have rechipped them at no charge. Of course there's no way to predict if the Sigma lens will work with an EOS DSLR released next year or the year after that or the year after that. It may be just fine. However there has been a history of issues and I've no idea if Sigma have managed to engineer around that. Some Sigma lenses in the past have also shown reliability issues. Again though, that's in the past and current Sigma lenses may be just fine. There's really no way to tell and I'm prepared to give them the benefit of the doubt here.

The downside on the Canon lens is the cost. It's $380 more expensive. Make that $425 if you include a lens hood, and make that around $500 if you add on a 3rd party extended warranty to match that of the Sigma lens. The Canon I tested also showed zoom creep. I'm charitably attributing that to previous heavy use as a Canon "loaner" lens, but nevertheless it does show that it can happen in time at least to some samples. I'm sure it can be fixed, but not for free if the lens is out of warranty.

So in the end it comes down to dollars and cents. I would be hard pressed to say that the Canon lens is worth $500 more than the Sigma. I might be prepared to pay a $100 premium for it, maybe $150, but not $500. The Sigma lens is clearly a better bang for the buck, though I'd still rather have the Canon if money wasn't a factor. Unfortunately money is always a factor.

You can't really go wrong with either lens if you need a fast normal zoom for a crop sensor DSLR. Sorry to be equivocal about this, but these are both good lenses with nothing (other than cost) that clearly points to either one being the "winner". If I needed a lens of this range and speed I'd be happy with either one. In reality I don't normally need the speed (and if I did I'd probably use a fast prime). If a wanted a general purpose wide to short tele zoom I'd probably look at the Canon EF-S 15-85/3.5-5.6IS USM for it's wider zoom range. However it is a stop or two slower which could be a deal breaker for some applications such as shooting in low light or at fast shutter speeds or blurring backgrounds. In those cases f2.8 would be a distinct advantage.

Finally I should mention the third member of this trio, the Tamron AF 17-50mm F/2.8 SP XR Di II VC. Unfortunately I did not have one available to me at the time of this review, but it shares the same zoom range and aperture as the Canon and Sigma lenses and it also has optical stabilization (VC). It's priced at around $650, so it's the least expensive of the three lenses (but only by about $20) and is certainly worth considering. Like the other two lenses, it uses low dispersion glass elements and three aspheric elements. User reports seem generally favorable and if I get a chance to try one out, I'll certainly post a review here.