Which Telephoto need advice

I have a 30D with a 24-105L and a 70-200 F4L as my only two lenses. This pretty much keeps me happy as far as range goes. But I see the 70-200 overlaping with the 24-105L a bit. I want to replace the 70-200 f4L with something else but I'm not sure wich way to go. I usually use it to shoot soccer, football, and baseball. Most of the time the lighting is good but at times when the games run into dusk or is over cast in order to keep my shutter speed up there I need to crank my ISO. As far as more reach, its always welcomed but not necessary, I think speed is more usefull but I want good optics and avoid too much overlap.I know that is alot to ask for. From these lenses what do you guys think would be best for me?? Prices are just an average I don't want to spend too much either, is there any other lenses I missed or I should consider or you recommend??? I wish there was a 100-300 2.8 out there it would compliment my 24-105mm perfectly.

Sigma 70-200mm F2.8 EX DG/HSM $750
Sigma 100-300MM F/4 EX APO DG IF HSM $825

Canon 70-200 F2.8 $1,100
Canon EF 70-300 MM F/4.5-5.6 DO IS $1,100
Canon 100-400 L IS $1,400

Heard a lot of good things on the Sigma 70-200mm F2.8 and they're a lot cheaper than the Canon 70-200 F2.8

If you're going for speed you could do one of the 70-200 2.8's, either Sigma or Canon non-IS'ers or the canon IS version. Then if you found you needed more reach you could slap on a teleconverter.

You've already looked at the Sigma 100-300, while it doesn't give you much more speed on the wide end it'll still give you F/4 on the long end plus some extra reach. I've read it takes TC's well too.

Now, depending on your budget you could look at the Sigma 120-300 F/2.8. It's got the reach, doesn't overlap with your 24-105, would take teleconverters for more reach, and has the speed for dusk sports shooting. It also has a hefty price tag.

That's about all I can see for zooms, depending on your needs and shooting style there's lots of prime options out there as well.

I thinking about going with the Sigma 70-200mm F2.8. Does anyone know how much more shutter speed you get with a F2.8 vs F4 if you shoot at lets say 1/500 F4 how much more faster can I go if Iswitch to an F2.8???

93octane wrote in post #2125400
Does anyone know how much more shutter speed you get with a F2.8 vs F4 if you shoot at lets say 1/500 F4 how much more faster can I go if Iswitch to an F2.8???

1/1000th and less DOF.

93octane wrote in post #2125400
I thinking about going with the Sigma 70-200mm F2.8. Does anyone know how much more shutter speed you get with a F2.8 vs F4 if you shoot at lets say 1/500 F4 how much more faster can I go if Iswitch to an F2.8???

It's one stop, so double the shutter speed. From 1/60 to 1/120second, or as you asked, from 1/500 to 1/1000 second. You also get the same results from bumping your ISO up one step.