Mark, would you consider the Sigma 18-50mm to be of a higher quality than the kit lens for a walk around? As far as the Sigma 28-70, I feel like it would nice to have the lower apeture as it would be easier to use for concerts but from what BoYFrmSpC said, I'm worried that it won't be wide enough for urban shots which I will be taking plenty of next year.
As far as the zoom and prime it looks like I'll be getting the Sigma 70-300 and the Canon 50mm. I meantioned this in another thread but what makes the APO lens so much better than the non-APO?
Thanks again for all the advice.
Do you need f2.8 throughout for a walk-around lens, I decided not as I have the 50mm f1.8 and 85mm f1.8 for wide aperture work so as mentioned the Sigma 17-70mm f2.8-4.5 is my lens of choice and find it to be very good. The Sigma 18-50mm f2.8 is not a perfect lens by any stretch which is a shame, but neither is the Tamron 17-50mm f2.8 if I were you I would check out http://www.photozone.de/8Reviews/index.html
which will give you more detail on both.
The only quality performer in the walk around f2.8 (assuming you are talking going out to 17mm) is the Canon option, again has flaws but is a lot stronger than the two above.
As for the difference in APO and non-APO is thatsome of the glass isAPO
chromatic basically higher design/build quality giving sharper results with better contrast/colour reproduction through the lens.