How to keep background in focus when shooting indoor basketball on a t5i 18-135mm

[PCarroll]

I am new to this and so far I love my camera. However shooting these games is sometimes difficult.  How do I keep the background from being out of focus. Sometimes using the auto focus it catches someone's arm that closer than the intended subject and I miss the shot. How do I avoid that. Your help is appreciated.  Thanks

[TCampbell]

To increase the range of distances at which subjects will appear to be in accurate focus (relative to the intended focus distance) you have to shoot at a higher f-stop (focal ratio or "aperture value" -- this is the "Av" setting on the camera).  

But it's not quite so simple to get that result.  Each time the aperture value inceases by one "stop", the amount of light collected is "halved".

So ideally you'd use an f/2.8 zoom lens like the EF 70-200mm f/2.8L IS USM II and you'd use that lens at f/2.8.  But if you increase to f/4 (that's one stop) the light collected through the lens is halved and now you either have to double the ISO sensitivity OR you have to slow down the shutter time so that the shutter is open twice as long (to compensate for the fact that the lens is now collecting half as much light.)

Ok... suppose you were able to shoot at 1/1000th.  Now you're down to 1/500th.

But f/4 is still a pretty low aperture value and not much will be in focus.  If you stop down to f/5.6 (another full stop) you've got to slow the shutter speed again... now you're at 1/250th and f/5.6 is still a bit low.  You're now collecting just 1/4 of the light you were getting at f/2.8.

Stop down to f/8 and you halve the light again... but now your shutter speed is at 1/125th and that's NOT fast enough to freeze any action.  Everyone will  be "in focus" but "blurred" due to motion.  Also you're now getting just 1/8th of the light you had at f/2.8.

If you could go to f/11 you'd have fantastic depth of field, but now you're getting 1/16th of the light and you have to shoot at 1/60th.

The solution is (you're not going to like this):  Just add 16 times more light to the room and you can shoot at f/11 without having to slow down the shutter speed at all.

Of course you can't realistically add 16 times more light to the room.  And most venues probably wont let you use flash and even if you could you'd then have to deal with the light "fall off" problem (specifically you can lookup the "inverse-square law").

And THAT is why sports photographers use f/2.8 glass and learn to be clever with their focus system.  You can't get everything in focus, but you can be quick about getting your intended subject in focus.

[ebiggs1]

Tim you kept mentioning slower down the shutter but the OP should look at increasing the ISO first.  Max it out to what is acceptible before you start to slow the shutter.

Although 1/125 is not as good as a faster shutter, it will freeze some or most BB action.  Especially if you are not at the 200mm end of the zoom.  Plus some arm blur or ball blur can be very nice.

Even though all this depends on the venue.  I have shot some HS, BB, games where the light was pretty decent, some was not.  But max out the ISO first as the T5i can do very well there.