Canon EOS 5D Mark II - EOS 5D Mark II 21.1MP Full Frame CMOS Digital SLR..., Service Manual

Page: 82 / 285

Technical Information
9
５）AI SERVO AF
⑴Predictive AF computation
Predictive AF can focus track a subject
approaching at 50 kph up to 8 meters
away with an EF300mm f/2.8L IS USM.
As with the EOS-1Ds Mark II, the EOS
5D's predictive AF computation uses
statistical prediction that incorporates the
focusing data of past focusing operations.
Since it can repeat more focusing
operations in a short length of time, the
predictive AF control can effectively
operate from the first shot even for a
subject moving erratically.
Also, even if the subject movement
changes right before the shot is taken,
the predictive AF control will have a good
chance of catching it.
⑵For still subjects
Even for still subjects in the AI SERVO AF mode, the focus control is stable so that
the lens drive does not move minutely. If the subject has major movement, the focus
detection is always active to enable subject tracking.
⑶Single-stroke, complete pressing of shutter button
As with the EOS-1D Mark II, when focusing is possible, the lens drive is executed based
on the focusing result right before shutter release.
６）Automatic AF point selection
Automatic AF point selection uses a new algorithm designed for the wide-area, 9-point,
One-Shot AF and wide-area, 15-point and 7-point center AI SERVO AF. The automatic AF
point selection speed and the AF point selection accuracy (matching the user's intended
subject) are as good as or better than the EOS 20D's.
Fig. 018 Predictive subject tracking with
AI SERVO AF
100
[m]
10
1
5 10 50 100 500
8
20
Subject's speed (kph)
S
ub
je
ct
dis
ta
nc
e