2 main contenders, will there be much quality difference

ok so i am in need of purchasing a zoom lens for when i go to car races etc and noticed that you can pay a fair whack for one. even though im studying photography at college i dont fancy spending 1000 quid plus on a zoom lens. anywya the 2 that i have seen are these, can you tell me if there would be much quality difference between the two and i mainly shoot in dark forrests, (mountianbiking) and at car and rally events.

http://www.jessops.com …non%20AF)-74238/Show.html

or

http://www.jessops.com …SM%20Lens-22119/Show.html

which would you go for, as im not really knowlageable as most people when it comes to choosing lenses

cheers, phil

With you studying photography at school, do they not have equipment you can sign out?

I'd personally go with the Canon as you probably won't need f/2.8 at the races. The IQ on the 70-200/4 is very good.

i don't think there will be a huge difference in quality.

all the 70-200s are comparable.

I had a similar choice to make last year and went with the Sigma. I haven't regretted my decision. It's an awesome lens.

I think you'll likely find 70-200 on a crop body far too long to shoot mountain biking. I don't know what your particular trails look like, but you'd have to stand a good distance back and hope there aren't any trees in your line of sight to get any decent pictures.

But if that's not the case... and as you also need it for rally car, there won't be a big image quality difference, but the Sigma will not auto focus as fast as the Canon. With action shots, that can be pretty important.

And if you want to go even cheaper, copies of the Canon 70-210 F/4 pop up from time to time on ebay. Again it doesn't have the USM auto focus that the L has, but for around $150 USD, it might be worth trying (and re-sell if you don't like it, glass like that won't go any lower in value) and leave you a little money for something a bit wider if you need it.