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cgratti
22nd of December 2006 (Fri), 22:52
I was reading on the custom functions, I can't seem to get this to work.

I adjusted Cfn 4 to #3. When I press the * to focus (center point), it wont focus!!

I followed this to set it up.
Jman13
22nd of December 2006 (Fri), 22:53
It won't attempt to focus at all? Remember, in servo, you won't get a focus confirmation light. If the CF is set correctly, an there is no AF at all going on, the only thing I can think of is that your lens is switched to manual focus!
cgratti
22nd of December 2006 (Fri), 22:54
When I press the *, I get the center point lighting up. No focusing.
Dan-o
22nd of December 2006 (Fri), 23:15
As Jman said you will not get a beep that it is focused. Does it look focused in the viewfinder?
cgratti
22nd of December 2006 (Fri), 23:17
Ok, I'm an IDIOT. I was pushing the FOCUS POINT button, not the *. Now it focuses perfectly.

Next question, when shooting must I hold the * button down to keep the lens focusing? Or once it locks on can I let the button go and it will stay focusing?
ScottE
22nd of December 2006 (Fri), 23:50
The advantage of using CF 4 and AI Servo is that you have an instant choice. You can push the * button to get focus, then release and recompose, just like you would with One Shot mode. You can keep the * button pressed and the camera will track focus in AI Servo mode.

The purpose of CF-4 is to allow you to control when the camera will auto-focus. The last thing you would want it to do is to continue to keep on focusing after you release the * button.
DegasGoneDigital
24th of December 2006 (Sun), 09:11
It will stay in focus as long as your subject stays at that distance. If the subject is moving you will have to: 1) push the * to focus once the subject stops or 2) hold the * button down so you can track focus while your taking shots at the same time...
Mike K
24th of December 2006 (Sun), 14:35
Lots of good suggestions here. For a very education and comprehensive discussion on AF and use of AI servo, particularly with the ID series (but in part applies to crop Canons too)
http://www.photoworkshop.com/canon/EOS_Digital.pdf
Mike K
Gatorboy
24th of December 2006 (Sun), 17:41
Ok, I'm an IDIOT. I was pushing the FOCUS POINT button, not the *. Now it focuses perfectly.

Next question, when shooting must I hold the * button down to keep the lens focusing? Or once it locks on can I let the button go and it will stay focusing?

Keep the * button pressed. Only release it when you want to STOP focusing (i.e. Someone runs in front of your subject and you don't want the focus to pick up on that)