Canon or Tamron

50mm f/1.8 might be good addition to your kit if you don't have it already.

By the way, I still have this lens for sale !!!!

Keith..

Thanks for all the contructive advice and replies folks, very helpful.

I already have the 50mm F1.8, which is excellent, so my objective is to go for more sky with the shorter focal lengths

Hey Steve, an economical approach to the "more sky" approach is to get a 28mm f2.8 prime lens from Ebay or whereever - this will likely be better than any zoom as it will have much less glass in it which is very much a factor with astro subjects. Prime lenses wider than 28mm are available but the price tends to go up rapidly - a 24mm is likely to be twice the price.