Canon 1D Mark III autofocus



Sequence 1:

focus is on the player with the ball, but a split second later, it has shifted to player 26 entering the inner AF circle closer to the camera than the other players - lesson 1 - AF will tend to focus on the closest player within the AF circle.

Sequence 2:

Geelong's Tom Hawkins kicking for goal - initially good focus but inexplicably focus is temporarily lost then regained in this 10fps burst. I have included the full image and a enlarged crop to demonstrate the focus. No player entered the scene, so why was focus lost and reverted to the foreground grass?

focus is regained - presumably camera's AF algorithm detects closest moving object.

2 frames later, focus starting to be lost again - presumably as subject is now outside the inner AF circle.

Lesson 2: keep the subject within the AF circle instead of trying to compose the image.

Sequence 3:

Lesson 3: this confirms lessons 1 & 2 - keeping subjects within inner AF circle and avoiding closer subjects entering scene ensures AF is maintained - in this case on every frame of this 10fps burst.

Sequence 4:


AF not yet achieved as camera just moved onto this subject.

Lesson 4: AF is achieved quite rapidly in this conditions and works well to follow the closest moving subject within the inner AF circle.

Sequence 5:

2 frames later AF is inexplicably lost.

Lesson 5: can't always predict AF will work through a sequence.

see my more descriptive photo story of the game here: sports - Geelong vs Essendon July 2007