I take photo's for fun, or to remember events and people. I've ended up with a selection ofto help me achieve that, ranging from wide angle through to telephoto. Last year I tried to photograph my daughters netball games, and found great difficulty using any I had! I have searched the web, and by far the most commonly recommended focal length for netball is a 70-200mm zoom. This is recommended, whether the question relates to full frame or "crop" camera's, seemingly regardless of any other factor. But I can't see why!
My daughters games are outside, in the morning, and is therefore plentiful. Spectators (parents!) are courtside, minimal distance to the players. Movement with a camera is hard, simply because someone will step in front of you or want to chat. The best option seems to be to pick a place on the sideline and camp for a quarter. The best place on the sideline is dependent on the position your subject is playing - for example there seems no point in taking pictures of the back of a shooter at the other end of the court!
Assuming that the above makes sense, I did some tests. I measured out a fake court, and used my daughter and her practice "hoop" to take some pictures. No regard to etc., just framing. Using old 75-300mm and 28-80mm zooms on my 7D, 70mm is far too big for using under the goal, unless you just want a face. 200mm is fine for tight framing when the players are "half a court" away, but 100mm is still usable with some cropping on the computer. 70mm is not quite enough reach.
As far as I can see, 70-200mm would be a good focal length for those conditions on a full frame camera, though I'd probably still want something shorter under the hoop. But on a 7D I really can't see it as a good solution. So why is it so often recommended?
I already have a 100-400mm zoom, a great , but when I tried it for netball it wasn't fun. Too long for the baseline, too long for the sidelines unless the play was at the other side of the court. Step backwards and the viewfinder is filled with the back of someones head!
I also have a 17-55mm, which it my most used . Great under the hoop, but too short everywhere else. So if your subject is a goal shooter you're OK, but not so much for a more mobile player.
From my backyard experimenting, it looks like the 24-105mm f/4L would be the best choice as a single . In fact a touch longer would be nice, but the available aren't weather sealed and it's either dusty or (rarely) raining! I also realize that choice is personal, that f/4 is slow for indoor sports etc., but disregarding all that I still think that 70-200 is too long on a 7D. Yet people asking the question with most or all of the same restrictions I have (crop camera, daytime outside, courtside etc.) are still told "70-200mm".
So what am I missing? Or does it relate to the mystique of the in question, rather than the focal length?