50D Focus lock...how?

Hey guys...Shooting some sports and some weddings and was just wondering how I could achieve focus lock on the 50D? I want to be in AI Servo so I can focus on moving objects, but there are times where people are standing still and I dont want the focus jumping around on me. I want to just set middle focus on camera,focus on the eyes with middle focus point, have it lock, then reframe the image and shoot. This should keep the focus where I locked it no matter where I frame the shot so the eyes will be in focus.

My problem is, I know it can be done, but I dont know how. Anyone know how that would be willing to help?

Are you using back button focusing?
If so, do you have the shutter button set to "AF Start/Meter Start"?(not sure which Custom Function this would fall under for your 50D..)
If you set it so that your rear button is for AF start, and the shutter button is ONLY for AE lock/Meter start, you can focus and recompose as wanted.

Focus with thumb, shutter with index finger..

When set to AI Servo, you simply PRESS and RELEASE the AF button for "one shot" focus, or you HOLD DOWN the AF button for Servo focus/tracking..
I just learned this trick from someone here a couple weeks ago, and this is sooo much fun. no more having to switch between AI and One Shot, just PUSH or HOLD the AF button for whichever "mode" you want..brilliant.

FWIW I have my 5D2 and 60D setup to only Meter Start/AE lock(?) on the shutter button. and the AF is set to "AF Start"..
Not sure if there is a better way to set it up or not..I am sure there is..but this works wonderfully for me

Hope this helps

You can turn off autofocus on the lens and lock it that way as well.

HyperCams wrote in post #14775977
When set to AI Servo, you simply PRESS and RELEASE the AF button for "one shot" focus, or you HOLD DOWN the AF button for Servo focus/tracking..

Hope this helps

Awesome, Ill try that! Thanks!

If you're not using back button focusing then you'll have to switch quickly form AI-SERVO to ONE-SHOT... it shouldn't take *that* long to do, but depends on what you're shooting I guess...

If there's lots of variables that mean you can't quickly change the focus mode then it sounds like back button focusing will become your best friend!

But doesn't using AI Servo disable the AF assist beam if you are using flash?

Yes it does. Then whether that's a problem or not depends on the conditions.

apersson850 wrote in post #16521847
Yes it does. Then whether that's a problem or not depends on the conditions.

I like every advantage I can get at my finger tips.