Canon 1D Mark III autofocus

• see also:
  • Canon 1DIII AF tests - take 1

  • Canon 1DIII AF tests - take 3 - success!

  • see my more descriptive photo story of the previous game here: sports - Geelong vs Essendon July 2007
  • 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 here: Canon 1DIII AF tests - take 1
• This game, I decided to give it another go, this time changing the AF setting to ignore foreground obstacles as on the previous attempt it would often suddenly change focus to foreground grass.
• Again, 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.
• images are straight jpegs from the camera with no PS processing other than cropping &/or resizing plus compression for web.

Sequence 1:

First I thought I would try the EF 135mm f/2.0L with 1.4x EX II extender in AI Servo with AF setting to ignore foreground obstacles and used ISO 3200 to give 1/1600th sec to minimise camera shake or subject movement causing unsharpness.

I used the AF-ON button to set focus whilst attempting to ensure the subject was on the center AF point to acquire focus

This whole sequence ended up the same - nicely in-focus advertisement banners in the background but out of focus players.

I am guessing the main problem here is that unless the player fully covers a AF point then the AF point selects the background.

This may be remedied with the new firmware upgrade.

Sequence 2:

Worked out how to get 100% of the sequence in focus - use manual focus with a $50 lens from Ebay, the Sigma 70-300mm f/4.5-5.6 for Olympus OM mount - here I have used ISO 6400 to cope with f/5.6 at 300mm:

the whole of this sequence was in focus BUT it required pre-focusing on a predicted zone of action.

Unlike the AF, there is no evidence of players going in and out of focus as with the current AF mechanism.

Sequence 3:

An advantage of the manual focus method is that even if the players fall out of the AF sensor ring, they still remain in focus:

and another example of manual focus:

and..

BUT there is a big problem with manual focus - if the action quickly moves to a different zone, you will miss shots as manually acquiring new focus takes time.

Conclusion:

I went back to the AF lens and had mixed results - much more reliable when the action was close and filled much of the central region, very unreliable when players at 60m as with sequence 1 above, presumably as dominant central AF point selects background or foreground in preference to the players.

A solution (assuming no improved algorithm from Canon) in this scenario would be to get closer to the action with a 300mm f/2.8 or even a f/4 lens so the players fill the central AF region more completely.