I agree with mark here. My main product photography lens is the Sigma 24-60 2.8 ex lens. It has very close focus, about four to six inches off glass so is perfect for small products, but wide enough that its great for large products as well.
I read reviews upon reviews deeming the 24-60 was much sharper at corners than the 24-70 version and was also sharper at long end (although not as long) but and they were both sharper than the tamron 17-70.
I was ready and willing to purchase the sigma 24-60 or 24-70 but I found the sigma 24-60 first and fir a nice price.
Im extremely happy with it, if you are interested I can post some pics I took with it.
Edit: it also make a gorgeous portrait lens, and excellent landscapes, but I do prefer my primes with landscaping, not really so much for the sharpness because this lens is incredibly sharp, just mainly because of the unrivaled coloring Ive seen out of my CZ glass. although the sigma comes extremely close, which says alot for a zoom lens to hang in there with the big boy primes! Also, My favorite portrait lens is my cz 200 2.8, but I interchange between the 200 and the sigma 24 60 depending on whether im shooting close or far. 24mm is wider than you think, especially when it close focuses, youd be surprised. for example, I can stand about 6-10 feet back from a car and get the whole thing in frame, (a classic pontiac grand prix full size sedan for example) with pretty much no distortions, I cant see why youd want anything wider unless you're looking for that sigma 10-20mm look
Last edited by NMRecording; Sep 11, 2010 at 11:31 AM.