AI Servo AF tracking duration and speed

[Alan T. Price]

I'm using a 1D2.

I was wondering if anyone (like Chuck) can tell me for sure how long the AF tracking continues to operate after I release the AF button, be it the * or the half-pressed shutter button.

My concern is that I can release the AF button accidentally and momentarily when I'm intending to hold it in, and I'd like to know if I do that how long the AF will continue to track the subject. Asume of course that the AF sensor is still on the subject.

The worst case is that the AF stops and then has to re-aquire the subject and track it's motion again. Can anyone tell me how long that normally takes ?

thanks in advance

- Alan

 

[Nill Toulme]

It stops pretty well instantaneously when you get off it — as it should. This is one of the main reasons I like using the * button via CF4-3 so much. It makes it much easier (than the half shutter press) for me to keep AF active as I'm tracking an athlete and sporadically releasing the shutter.

Nill
~~
www.toulme.net

 

[Chuck Westfall(Canon USA)]

Hi, Alan:

Nill is right, AF tracking in the EOS system stops immediately if you release the camera control that's being used to activate it. This allows photographers to control camera performance as precisely as possible.

There are no statistics on how long it takes for the AF system to acquire a moving subject, mainly because there are too many variables. But as I've stated elsewhere, you can use the camera's in-focus indicator indirectly in AI Servo mode to determine if the camera is or is not tracking the subject.

Please refer to page 8 of "Camera Handling & Maximum Image Quality" for a detailed explanation.

http://photoworkshop.com/canon/EOS_Digital.pdf

Best Regards,

Chuck Westfall
Director/Media & Customer Relationship
Camera Marketing Group/Canon U.S.A., Inc.

 

[Asher Kelman]

Chuck,

to what extent might a 1.2 lens speed the acquisition of focus?

Asher