Specifications

Release/Tracking priority
Spot AF
C.Fn III-3: (AI Servo 1st/2nd image priority) has had the optional [3: Release/Tracking priority]
setting added. Shutter-release prior
ity (rather than focus priority) is given to the first shot.
During continuous shooting (from the second shot onward), stable focus-tracking of the subject
is given priority. This new setting, which was the only option for AI Servo AF release/tracking
priority with the original EOS-1D, EOS-1D Mark II and EOS-1D Mark II N, was
conspicuously absent on the EOS-1D Mark III. Now, EOS-1D Mark IV users will have the
best of both worlds together with the new improvements to AF hardware and software.
The new AF system allows for considerable customization, particularly because new controls
have been added to the complement of Custom Functions. For example, when C.Fn III-6-7
is set and you press the AF Stop button on a super telephoto lens that has AF Stop buttons,
the focusing line sensor’s usable area becomes narrower; the focusing field of view is reduced
by about half. The AF system can then focus on a smaller area, reducing errors caused, for
example, when a sensor sees a bit of extraneous background.
Some examples of situations in which Spot AF will be effective include staying focused on
the eye of a helmeted driver in an open-cockpit racing car, capturing an athlete on a distant
victory stand without using a telephoto lens and being confident the cropped photo will be
clear enough, capturing baseball players through the backstop and photographing wild
animals through trees in a forest.
Spot AF works regardless of the AF mode and AF point selection method. It is especially effective
for manual AF point selection. However, since the decrease in size may make it difficult to keep
the AF point centered on an erratically moving subject, focusing might be difficult. When starting
with a scene entirely out of focus, Spot AF focusing may be slow. As a reminder that Spot AF
has been set, the AF point display in the viewfinder will flash brighter than normal.
19
IV–1. NEW 45-POINT AUTOFOCUS SYSTEM
For spot AFFor normal AF
Spot AF (Conceptual Diagram)
First frame during continuous shooting All subsequent frames in burst
0
AF priority/Tracking priority
Shutter is released once subject is in
focus.
There may be a delay when image is
blurred.
Focus is prioritized.
Continuous shooting speed may slow down
depending on amount of blur , contrast and
brightness.
1
AF priority/Drive speed priority
Shutter is released once subject is in
focus.
There may be a delay when image is
blurred.
Continuous shooting speed is prioritized.
Continuous shooting may slow down
(depending on amount of blur , contrast and
brightness) but is faster than for tracking
priority.
2
Release/Drive speed priority
Shutter is released even if subject is out of
focus.
Continuous shooting speed is prioritized.
Subject tracking may not be active depending
on amount of blur , contrast and brightness.
3
Release/Tracking priority
Shutter is released even if subject is out of
focus.
Focus is prioritized.
Release timing may be delayed depending on
amount of blur, contrast and brightness.
AI Servo 1st/2nd Image Priority
f/5.6 sensor
f/2.8 sensor
Spot AF sensor area
(smaller)
Standard AF sensor area
Area displayed
on viewfinder
Cross-type AF sensor illustration