Sigma 120-300mm f2.8 vs Nikon 300mm f2.8

[391615]

Aside from the obvious what are the pros and cons for the cheaper lens vs the expensive one.

Would I lose image quality with the Sigma?
I'd be using the lens for sport, and prefer to stay on maximum focal length anyway.

I'd take the 400 2.8 if I had an unlimited budget.

 

[notelliot]

seriously?

 

[Overread]

The zoom (sigma) will be softer at 300mm than the prime (the nikon) and as you say you are staying at 300mm anyway the zoom really holds not bonuses for you - if you were expecting to shift across the focal range of the zoom a lot then I would recomend it, but as your not why spend for a zoom that covers focal ranges you don't need?
A zoom is often softer than a prime due to the extra glass needed in its contruction - a prime is far simpler in construction and needs less glass to get the desired focal range. Strangly Amazon does not list a nikon 300mm f2.8 (I don't know nikon range, so went there for some info). This might mean its an older lens and possibly manual focus only - write back and link to an example of the lens you mean -- or hope that someone will pass by who does know.
My money would be on the 300mm f2.8 prime lens unless it proves to be either without AF or very old - the lack of AF is debatable depending on the indevidual though

 

[Joves]

I agree with Overread on this. If when you are shooting sports form a side line where you will be going from long to short, then the zoom would be a better choice. If from the stands a prime will serve you better. Also what you have to ask yourself is are you staying stricly to sport shots or, will you use the lens as a general use lens as well.