What is a decent lens for a Nikon D7000?

Question

I have a D70 with the stock Nikkor AF-S 18-70mm 3.5-4.5G ED DX lens. Im about to replace the body with a D7000. I've found the 3.5 f stop a little limiting in terms of DoF - and having viewed some photos from a friend with an f2.8 lens am keen to get something that goes to this aperture/speed. Is the Nikkor 24-70mm f2.8 G AF-S ED the lens to go for? I mostly shoot my family in and outdoors and am really looking for some nice upclose head and sholder shots taken while kids play etc (Ie not posed). Should I go wider eg 17-55mm f2.8 G DX AF-S IF-ED? Later Id also be interested in the 70-200mm f2.8 G AF-S VR IF ED II zoom - which of the previous 2 would this go best with? Are there any cheeper alternatives to these lenses (which are pretty pricey..). Thanks all.

Edit: I should have mentioned that I have a Nikkor 50mm f1.8 AF prime that takes great shots - the issue here is that because Im shooting my family in action (kids at play, parties etc) I really need the flexibily of a zoom. A prime maybe OK if say everyone sitting round a table but when kids are moving, running round and playing you just cant move fast enough to keep up and frame a good shot with a prime (well I can't).

Answer

The Nikkor 24-70mm f2.8 G AF-S ED is a superb piece of kit, and priced accordingly. If your livelihood isn't dependant on getting absolutely optimal quality every time, you could consider a third-party alternative.

I use a Sigma 24-70mm f/2.8 Macro lens that's good enough 99% of the time, and costs less than half the price of the Nikon version. You should check that a third-party lens works with the D7000 before buying one. I've heard of incompatibilities between third-party lenses and cameras that didn't exist when they were produced but I don't know if there's any truth in that.

The 70-200mm f2.8 G AF-S VR IF ED II is the natural partner to the Nikkor 24-70mm f2.8 G AF-S ED because one picks up where the others focal length ends. It's probably one of the most common configuration in a pros kit bag (along with a wide angle and probably a 50mm prime, just in case).

If you use the the 18-24 range of your current lens in your existing photos, you might consider another lens. That's up to you.

Personally, I don't want to carry a 0.9 kg lens around with me all the time. If I were you, I'd go for a Nikon 50mm f1.8 D AF. It'll give you high quality images for a fraction of the price assuming you don't mind "zooming with your feet". That's what I use 90% of the time when I know I'm shooting people at a modest distance. Spend some of what you've saved on an SB-700 flash, which will give you far more flexibility.

If you find you need a bit wider (group shots or indoors?), there's a Nikon 35mm f/1.8. If you need to shoot from further away (sports, or just less distracting?), there's a Nikon 85mm f/1.8. Those will all work better in low light, and you can buy the whole lot for less than a Nikkor 24-70mm. You lose the ability to go from one length to the other in a twist of the lens, but you probably know in advance what length you'll be shooting at in a given circumstance. You save money and (more importantly) carrying weight.

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