I have been shooting for several years in the north of Canada and I notice that I don't get a really high percentage of keeper when using my Canon 100-400 Mk II or 70-200 F2.8 Mk II with either 5DIV or 1DX2.
Even after careful lens calibration, I often get a 50cm-100cm (20in - 40in) back focus which is problematic when shooting dog's face for example. In this case they are usually coming at 10-15 miles per hour which I try to capture at something like :
- 1/800sec - F5.6 - 400mm - ISO 1600 to 3200
- Subject is usually within 50m - 20m (150ft-60ft) away
- Speed 10-20mph
- temperatures around -20c to -45c (0F to -45F) which makes the camera a tad slow to respond.
- Subject with really low contrast
What would be the optimum way to achieve focus:
- 1 Would you use only one focus point or use an extended area focus?
- 2 One Shot AF to avoid using the tracking that doesn't seem to work anyway or AI Servo?
- 3 Which point would you use? I usually use the lowest points but looking at the picture below that might not be optimum?! a tad confused with that figure.
- A: Cross-type focusing: f/4 horizontal + f/5.6 or f/8 vertical
- B: f/5.6 or f/8 vertical focusing
- C: Cross-type focusing: f/5.6 or f/8 vertical + f/5.6 or f/8 horizontal
- D: Dual cross-type focusing: f/2.8 right diagonal + f/2.8 left diagonal f/5.6 or f/8 vertical + f/5.6 or f/8 horizontal
At that point I would take any advice! Maybe I am just not using the tracking properly... not sure! Also note that the cold condition makes it challenging to keep the tiny points on the subject which is why I usually end up using extended area focus which might be harder on the camera focusing wise.
Thanks for your input!