I am pretty much a lurker on this site, photography is a hobby I enjoy, unfortunately I don't have a whole lot of time to dedicate to it. I mainly shoot with my D70s and 18-200 VR1, but lately I have not been satisfied with the quality of images it produces. I rented a 17-55DX and was very pleased. So this leads me to my question. Is the Sigma or Tamron comparable to the Nikon? I would rent one if someone locally offered it and try it myself but that's not an option. I figured with the money I saved on the Sigma/Tamron I could get the 70-300VR.
The main difference is build quality and fokus speed. If you don't need the better build or the faster AF I don't see any point in spending all that money on the 17-55.
IF you have the money, then the Nikon is the clear choice. However, for most the Tamron should be more than enough. In fact, it's one of the only two 3rd party lenses that Thom Hogan recommends (the other one being the Sigma 10-20)
In terms of focus speed, the Nikon wins. No contest here. The Tamron and Sigma hunt in low light.
Optically, the Tamron is as good as the Nikon lens in terms of sharpness, except at f/2.8 around 17mm and around 50mm in my usage of it. From f/4 onwards at all focal lengths, I can't tell a Tamron 17-50/2.8 shot from my Nikkor 17-55/2.8 AFS.
Build quality is a no-contest win or the Nikon 17-55. You can kill a man with that lens, wipe the blood off, and keep shooting with it. Seriously... in the right situation, it's a self defense weapon AND photography tool.
I have the 17-55 and the AF is fast and it has great color and is very sharp, even wide open. The bokeh is pretty good, but not at the level of the best primes. The lens is huge though, and I still always ask myself why I keep using a zoom lens and not just sell it and get two primes that will be better and faster anyway.
17-55 is probably the best DX lens produced by Nikon but it's expensive and heavy. As it was said Tamron 17-50 is a good aternative... it's much cheaper and lightweight. You can buy the old version without AF motor or the new one that has an unbelievable good VC (like VR for Nikkors).
70-300, apart of some focal range wil not bring very much on top of 18-200. I rather recomend you Sigma 50-150/f2.8... You can add a TC when you need more than 150 but you'll have the whole 17-150 covered at f2.8 and that's very good.
I have the Nikon 17-55 with my D70 and really like the focus speed and accuracy in low light. It is rather large and a bit unbalanced for a D70 (I think) but it's what keeps dangling the D300s in front of me instead of the 7D because I do not like the Canon 17-55. I really like how the Nikon's hood is mounted to the body of the lens rather than the zooming mechanism (similar to the 24-70's).
One thing that has not been mentioned is that the Nikon 17-55 can be had for quite a bargain used nowadays, anywhere from $800-$900 for a used clean copy. That's a significant savings from new. Still more than the Sigman/Tamron, but something to consider.
I had the Tam 17-50 on my D700, and it was just great very sharp images all around, I need somethin just a tad longer and I went with the 24-85.2.5-4if, so I'm testing that now, but the 17-50 great, also had it on my D300.
Thanks for all the helpful replies. I'm going to go with a used 17-55, I really don't want compromise on the focus speed, since my main subjects are a 4 and 6 year old. Plus I'll check out the sigma 50-150 f2.8 instead of the 70-300 VR.
I was in the same dilemma a few months ago. I'm sure the Tamron has alot of pluses, but a personal anecdote on the build of the 17-55 - I was changing lenses on the bonnet of my car at night with no light (I know, dumb) when the 17-55 fell over and rolled down the side of the bonnet, smacked the pavement hard and rolled fast into a concrete curb. I was devastated until i picked it up, and found only the lens hood had scratched slightly. This thing is built f***** tough.
