Whether you want/need a long (telephoto) lens or not...is up to you. Do you want to get closer views or not?
What's your budget? And how much are you willing to pay for quality?
If you are going to be shooting moving subjects, especially indoors (in less than great light) then it would be a big help if you had a lens with a large maximum aperture. Unfortunately, a telephoto with a large aperture is going to be a large expensive lens.
Off the top of my head (without knowing more details)...my suggestion would be a 70-200mm zoom lens. Canon/Nikon each make their own version of a 70-200mm F2.8 with IS/VR. Top quality lenses....but very expensive.
Canon has three less expensive 70-200mm lenses in their line up...but you give up the large F2.8 aperture, IS or both.
Sigma & Tamron both make a 70-200 F.8 lens that is cheaper than than the Canon or Nikon. Quality might not be as good...but is still very good.
Agree, with some small points. It's four.
70-200 f/4 USM and IS USM
70-200 f/2.8 USM and IS USM
I had the f/2.8 IS USM and decided it was overkill. Sold it and just picked up a used f/4 USM, Non-IS. Used the extra money to buy a 100mm Macro and a 100-400 IS USM.
The f/4 lens is rated just as high as the f/2,8 for sharpness, which was a big surprise. If someone shoots outdoors in good light, most of the time, the f/4 will be fine.
If you are going to shoot indoors, might as well go all the way, IS USM f/2.8
IS lenses are weather sealed, non-is lenses are not. (if you shoot in the weather, this could matter) f/2.8s come with the tripod/monopod ring, the f/4s don't. The ring costs $149 from Canon, aftermarket around $60. Now that I have the f/4 in my hands, I know why most people don't need the tripod mounting ring for the f/4 lens. It's very manageable.
With that, the 70-200, any one of them, is a very sharp lens with a moderate and functional zoom range. Go test shoot one at a photo store.
Warning, you will be spoiled and your kit lens or non-L lenses will suddenly look soft in comparison. :mrgreen: