What is normal? Well, the 18-55mm kit lens that comes with the D40 is considered a normal zoom lens. I would really like something faster. This is a common theme with me and lenses at the moment. I am also not convinced that the lens I have is all that sharp, but I have yet to try to take real test shots.
So what are the contenders? First off, I am pretty sure that I don’t want to get another fast prime right now. I have the Nikor 50mm f1.8, and it should auto focus on the next camera I buy (doesn’t on the D40), and it is much faster. I like it, but it isn’t as versatile. It is too long for inside too. I could try a 30mm or some such thing, but then I would have no real wide angle at all. I figure that I will be selling the D40 with the kit lens, so I think that replacing it with faster glass with similar range is a good bet right now.
Nikor 17-55mm f/2.8 – $1200 – ouch – but the one the others are compared against
Sigma 18-50mm f/2.8 EX DC Macro HSM – $450 – has macro, but hit or miss I hear if your lens is sharp
Tamron 17-50mm f/2.8 XR DI-II LD – $450 – supposed to be good build quality and sharpness
Tokina 16-50mm f/2.8 ATX Pro – $660 – considered a pro lens like the Nikor, but haven’t heard much
I found a few reviews out there, like this one at SLRGear for the Tamron, but it is for the gear motor type. Should be similar. Most of the rest of the info I have found has been in forums or posts like this one on fredmiranda. It would seem that the Tamron is slightly in the running at the moment. Several posters seem to think the sigma isn’t as sharp.