For outdoor sports on larger playing fields, such as soccer, baseball or softball, and football, you need more telephoto power for effective, “tight” shots from the sidelines. Lenses like the EF-S 55–250mm, or the longer EF 70–300 lenses (there are several options in the 70–300mm category) will give you a lot more reach, to fill the frame with athletes. In daytime, their relatively modest f/5.6 maximum lens apertures won’t be a problem, as long as you’re not shooting in deep shade, or late in the day at dusk. On overcast days, expect to use higher ISOs to maintain the fast shutter speeds you need. Don’t be shy about using ISOs like 800 or 1600 if the light isn’t ideal, with these lenses.
Indoors, you need to think about lenses that let more light into the camera. Fortunately, there are some affordable options here. For sports like basketball, if you can position yourself under a basket (usually off to one side, so you’re out of the referee’s way), a lens like an EF 50mm f/1.8 is a wonderful way to suddenly “turn the lights on,” so to speak — it lets much more light into the camera than a standard zoom lens will.
A lens that’s affordable, but provides that elusive combination of added reach and still lets a lot of light into the camera, is the EF 85mm f/1.8. Like the 50mm just mentioned, it’s not a zoom — but especially with cameras using smaller APS-C size image sensors, it’ll give you added telephoto power, for sports like gymnastics, where you can’t get right up to the athletes.
The biggest problem for indoor sports, as you’re getting started in sports shooting, comes when you cannot get close to the action — think of sports like ice hockey, or night sports like football, soccer, or field hockey “under the lights.” (Or even indoor sports, if you are shooting from the stands.) Sometimes, the best answer is to simply crank-up the ISO on your camera to 6400 or even higher, and use a tele zoom lens, like one of the 70–300s mentioned above. Another option — which represents a bit of an investment — is to consider a fixed focal length, wide-aperture lens, but one at a price point that’s within reach of a dedicated amateur photographer. The EF 200mm f/2.8L II is a great example, and it’s a lens that effectively “acts” like a longer 320mm lens if you attach it to an EOS camera with the APS-C size image sensor (like an EOS Rebel, 80D, or 7D-series camera).