Canon EOS 1D Mark III User Guide - Page 20

Subject distance 100 AI Servo AF Predictive AF can track a subject approaching at about 31 mph [m] up to about 26.2 ft. away with an EF300mm f/2.8L IS USM lens. This is the same as with the EOS-1D Mark II N. However, improve- 20 10 ment in focusing detection performance enables subject 8 tracking at 10 fps. 1 During AI Servo AF when the camera is focusing on a subject 5 10 50 100 500 Subject's speed [Km/h] and something closer enters the picture, the camera can either start focusing on that closer subject or ignore it as an obstruction: • AI Servo AF tracking method > Main focus point priority (C. Fn III-4,0): The camera will start focusing on the closer subject that entered the picture. When the center AF point detects that closer subject, the focusing priority will then shift to the main AF point. • AI Servo tracking method > Continuous AF track priority (C. Fn III-4,1): The camera will ignore any closer subject entering the picture. The focus-tracking immediately before the obstacle entered the picture will continue, and the AF point can shift to any other one while tracking the original subject instead of being fixed at the main AF point. C. Fn III-3 (AI Servo 1st/2nd image priority) is for setting the priority on focusing or on the shutter release for the first and following shots during continuous shooting. 0: Focusing priority takes effect for the first shot as well as for the second and following shots with focus tracking. 1: Focusing priority takes effect for the first shot, and priority on continuous shooting speed (more than the focus tracking of the subject) takes effect for the following shots. 2: Shutter-release priority takes effect for the first shot (overriding focus). For the following shots, priority on continuous shooting speed takes effect more than with option 1. When "Focusing (subject-tracking) priority" is selected and the subject distance changes, the continuous shooting speed may become irregular. When "Drive speed priority" is selected, the focusing might be slightly off, but the shooting speed will be fixed. Setting 2 is effective for press photographers who put priority on capturing the moment. C. Fn III -3 can be set to change operation characteristics when you press the shutter button completely in one stroke. Settings 0 and 1 are the same as on the EOS-1D Mark II N. When focusing is possible, the lens is driven to match the focusing result obtained immediately before shutter release. After the lens is driven, the picture is taken. If focusing is not possible, the picture will be taken immediately. With setting 2, the picture will be taken immediately regardless of whether focus has been achieved or not. During low-speed continuous shooting, the subject distance can change significantly between shots. The slower the continuous shooting speed, the more the lens is driven between shots to detect the subject. Thus, subject tracking is more precise. Also, with the EOS-1D Mark III, the improved AF computing performance enables the lens to be driven more to detect the subject than with the EOS-1D Mark II N. AI Servo AF therefore becomes V. INCOMPARABLE EOS AUTOFOCUS, NOW EVEN BETTER 20