hello again, I know it seems I am asking a lot but I am just curious
I have been reading so much about lenses etc... since being told of Fred's site.
I want a wider lens, I have the sigma 24-70 EX I am real pleased with but looking for a little wider one. I like cript photos especially in the center.
I am looking at 2 lenses in the EX maybe would look at a Tokina also? but I feel confident with the EX series at this point.
I see there is a 15-30mm EX and a 18-50mm EX, which would you say is the better lens? the more length isn't as important as the wider lens to me. They are both pretty fast.
let me knwo
I have a Sigma DSLR and therefore use Sigma EX lenses. Like you, I have the 24-70mm EX and it is a very good lens. It could be sharper wide open but it sharpens up nicely as it closes. I know a number of other Sigma users and the newer version of the 18-50mm EX gets great reviews from them. The 15-30mm EX as well as the 10-20mm EX are regarded highly. For my Nikon DSLR, I use a Tokina 28-70mm AT-X. Like the Sigma 24-70mm EX it is soft wide open but sharpens up in the same manner as it closes. It also has amazing build quality. The 12-24mm AT-X is highly rated, it seems like a very sharp lens (it's not for full-frame DSLRs).
First, 15mm is really a lot wider than 18mm, although you'd think otherwise. And, the 15-30 lens is also physically a lot larger than the 18-50. The 15-30 also has a rather odd (although not for Sigma) arrangement of the lens hood and cap, which makes buying/using filters more expensive/difficult. Having said that, I enjoyed my 15-30 (on a 10D and then 30D) while I owned it, and it was very sharp, corner to corner, with pretty good color and contrast. They're also available at a pretty good price now, too.
I also had an 18-50 for a short while, and found it to be nothing special, and surely not nearly as good in any way as the Tamron 17-50, which seems a no-brainer choice in that price and focal length range. It's very close in image quality to the Canon 17-55 IS.
To confuse matters even more, how about the Sigma 12-24? That's the lens I ended up keeping, and it's a real favorite of mine. Super-sharp, HSM focusing, same weird hood/cap arrangement, big, but not too heavy, and also reasonably priced. And it's made for a full-frame sensor. 12mm is much wider than 15, once again by more than you'd think, and the 12-24 has very little distortion for such a super-wide lens (as compared to Canon's 10-22 or Sigma's 10-20).
