Can I unashamedly jump on to the back of this thread rather than starting another?
I'm after getting another couple of lenses for our 600D which currently has only the kit lens. I'm set on the 50mm f1.8 but was also looking for a zoom not dissimilar to those mentioned in the thread. I want to get some decent photos whilst in Barcelona of the buildings and open areas with people.
Am I best with the prime or zoom (or kit) for this purpose? I think I'd get a better feel if I took the body down to a shop to test some lenses out but a bit of advice upfront might make me look less of a tard.
It really depends on the type of photography you want to do. Personally I believe that every Canon owner should have the 50mm F1.8, that's a given.
As for a true "walkaround" lens - it all depends on your photography style. On a crop-sensor camera, you'll want a lens that goes from 17mm to *something*. Just remember that the larger focal length you cover in one lens, the lower quality the optics of the lens will be (as a general rule).
I've never been a fan of 17-200's, as they simply cover too much focal length in one lens, and the optical quality suffers as a result. 17-55 or thereabouts is a good compromise. Enough focal length to frame subjects, whilst at the same time keeping better optical performance. The 17-55 however is expensive. The 17-85 is also a good option, and less expensive (and better optically than most 17-200's)
The main problem with the kit lens is that its slow (does not let in much light).
Really can't go wrong with the 50mm though. Just be careful when using it at F1.8-F2.0 if your subject is close (i.e 1-2m) - as at those F-stops your total depth of field (focus) will be a matter of cm's.
So you'd suggest a lower f 17-55mm as a walk around? Would this port well to a full sensor camera down the line? I appreciate your point on the kit lens, when I was using it on holiday it was a bit of a dog to get a decent exposure on overcast days at sensible shutter speeds for hand held shots.
If you want to port a lens to fullframe later, just make sure its a EF mount, and not an EF-S mount.
The 50mm F1.8 works well for low light shooting, but its not a great walkabout lens as 50mm is a bit long, especially on a crop camera.
I'd suggest you take a look at the review list on Fred and Miranda. For Canon the lenses are split into two categories - zoom and prime. You can go through every lens on there, see the price, and see what peoples views are. Then you should be able to create a shortlist of lenses that fit your budget, and have the characteristics you want.