Portrait: Nikkor24-120 vs Sigma 24-70 vs Sigma 70-200

[goncalo]

Hi,

I just bought a D70S and already had a Tamron 17-35mm 3.5/4.5 and a Nikkor F50mm f1.8 (no good for a digital body). I've done travel photography so far.

I want to start doing fashion stories, so I've been looking for a good semi-pro lens.

Because of the range and because it's a Nikkor, I started out by picking the
Nikon 24-120mm f/3.5-5.6G ED-IF AF-S VR. The apperture (not 2.8) and (some) bad
reviews got me off that idea. Basically I like low light conditions, so 2.8 sounds
great.

I also realised that most of the lenght used for fashion is 50-150mm. So, I've
thought about:
- Sigma 70-200mm F2.8 EX APO HSM
or
- Sigma 24-70mm F2.8 EX Aspherical DG DF
or
- Nikkor24-120mm f/3.5-5.6G ED-IF AF-S VR

The lenses are not so similar and I do think that the Sigma 70-200mm
(150-300 on digital bodies) is too 'narrow'.

Can I get some input on this? Any downside on the Sigmas / ranges?

Thanks a bunch!,
Gonçalo