focus problems with 50mm 1.8 lens

[dlutmer]

I am shooting with an EOS Rebel XTI and using a 50mm for gym/basketball shooting. It works great for the low lighting but I am having problems getting clear pictures. I can't use the center focal point because of the action in the games, so I have it set to all points. I'm not sure the best way to set this, so that I get focused image. Some turn out great, but many are not. I am using a tripod. Thanks for any tips!

[ScottyP]

You should expect a pretty high failure rate.  Fast-moving targets in dim light is about the worst possible shooting condition.

Shutter speed:  The tripod will not help you in sports.  Your problem is not camera shake; it is subject blur due to the moving subjects.  You would need a pretty high shutter if your subjects are moving in order to freeze them.  Like 1/200th minimum, even on a 50mm lens..

Camera:  The XTi is older, and its autofocus is not the very best at tracking moving subjects.  Something like a used 7D, or even a new T4i would be much better.

Lens:  I love my nifty fifty, but it is not the fastest focusing lens in the world.  A basketball game would be a challenge for it.  A 50mm lens is a little short for sports anyway, so perhaps at some point you would do well to get a lens that is both longer and faster-focusing.  An 85mm f/1.8 would be only about $375.00.

My advice is to lose the tripod, set your camera to continuous shooting, keep a shutter speed of at least 1/200th, and to take a whole lot of shots so that you get enough keepers.  You can also try to fire off shots when your subjects are not moving very much.

Good luck!

[dlutmer]

Thanks for the tips. I feel like some of the blur is definitely the motion, but some are overall bluriness (background, bleachers etc). I guess I'll keep doing what I'm doing...taking 300 pics a game and picking through the couple good ones!

[ScottyP]

Dlutmer,

Another hurdle is the super-shallow plane of focus you are getting with a wide f/1.8 aperture setting.  At that wide an aperture, only one thing is going to be in focus (probably just part of that one thing, if you are less than 20 feet away).  Everything else, like most of the other players, and definitely the background, will be out of focus. 

At that high shutter speed, there will be no camera shake effect, so you can discard the tripod.  With your camera off the tripod, you can follow the action with your camera.  This should help the camera to focus, and to focus hopefully on what you would like to focus on rather than whatever random thing the camera decides to focus on.  See if you can make the center AF point work for you so that you can better control what one thing the camera focuses on.

[cicopo]

Once again I'll say I haven't shot a Rebel body so there's a chance this isn't all going to be applicable but the first suggestion should. Set the camera to AI SERVO so that as long as you are pressing the shutter buttom  (or rear AF button) half way the AF will constantly track the movement. You DO NOT want it set for ONE SHOT. Also check in the custom settings (not sure these are available on a Rebel) to see if you have a setting in the AF menues that allows you to instruct the camera to IGNORE a sudden interuption between you & what you're tracking. (you're focused on the player with the ball but if someone runs through the area between you & that player the camera ignores him & stays on the player with the ball).

[ScottyP]

Yes.  An important clarification.  Continuous shooting mode WITH AI Servo AF mode.