Canon 1D Mark III autofocus

• see also:
  • see my more descriptive photo story of the game here: sports - Geelong vs Essendon July 2007
  • Canon 1DIII AF tests at the footy - take 2
  • Canon 1DIII AF tests - take 3 - success - the secret to good results at football!
  • Canon 1D MarkIII
  • Canon 1D Mark III wide angle lens tests
  • lens tests - Canon 1D Mark III vs Olympus E510 
  • Olympus E510
  • E330 lenstests 1
  • E330 lens tests 2 - super telephotos (200-350mm actual focal lengths = 400-700mm effective)
  • E330 lens tests 3 - 50mm lens shoot out
  • Olympus E330
  • E330 with OM lenses
  • Olympus E330 macrophotography
  • Olympus E digital
  • Olympus OM
  • lenses and lens testing
  • Olympus C8080 lens tests

Introduction:

• Firstly, I am no sports photographer, I bought the Canon 1D Mark III as a complement to my versatile Olympus dSLR kit for its low noise at high ISO, wide 14bit dynamic range, ability to blur backgrounds and its tilt-shift lens.
• However, seeing I have bought in and I was going to one of my occasional football games, I thought I would check out its much-touted but seemingly problematic ability to rapidly autofocus in action sports situations.
• I also took the opportunity to play with its 10fps shutter and its 6400ISO setting.
• In general, I am very impressed, its not perfect, but it did very well.
• I took with me my Canon EF 135mm f/2.0L lens with EF 1.4x II tele-extender to give me 189mm focal length, which, with the 1.3x crop of the APS-H sensor gives a 35mm film effective 246mm focal length at f/2.8 - all images taken at wide open aperture with lens hood in place and AF mode set to AI-Servo with AF menu settings as per default settings.
• some images were taken using only centre AF point, but most were in the 49pt mode - unfortunately I can't remember which photos were taken in which mode.
• no in-camera noise reduction used
• images are straight jpegs from the camera with no PS processing other than cropping &/or resizing plus compression for web.
• the camera usually acquired AF within approx. 0.5sec (this is a guestimate) but sometimes inexplicably lost focus and regained it during a 1sec sequence at 10fps.

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