Lens question for Rebel XT

[Motegi]

What midrange budget lens would you recommend to use with a Rebel XT for race action photos?

I'm thinking about the Sigma 70-200/2.8 HSM APO EX. Is that a good choice? and possibly add a teleconvertor to this?

I know the Rebel XT has a 1.6 conversion factor so the equivalent focal distance in 35mm terms using just this lens would be 320mm. Is that not enough? Also would the teleconvertor be detrimental by "slowing down" the lens by a few stops?

I have a low budget Canon EF 75-300 f/4-5.6 III lens right now (480mm equivalent focal distance) but am not sure if it will be up to the task. Do you think that this lens is too slow?

[ryans]

I think your current 75-300mm lens would be a decent lens to start out with. You can shoot very far with 300mm. I've heard from most pro's that if your shooting over 300mm you should get closer to the subject.

I also found for myself using a UV filter is good enough. I used a polarizer a few times and wasn't too happy with the results.

I was actually using a lower version of the lens you have and the results were actually quite good. I shot these galleries with my 100-300mm non usm lens. The last 2 galleries were with a 300D so it was even harder to get a good focus on it because I didn't have AI servo.

http://www.sromagazine.com/events/thumbnails.php?album=347&page=9 On Up

http://www.sromagazine.com/events/thumbnails.php?album=343

http://www.sromagazine.com/events/thumbnails.php?album=300

If your shooting action shots see if you can use AI Servo mode for the autofocus. This will really help getting good shots. You can hold down the shutter button half way and the auto focus will continually focus on the subject as it moves near or away from you.

[PNG]

I shot for OverRev for more than a year with my Canon 70-300. It's just fine for everything except low light.