Canon EOS 90D Advanced User's Manual page 318

Movie Servo AF
Cautions When [Movie Servo AF] is Set to [Enable]
o Shooting Conditions that Make Focusing Diffi cult
• A fast-moving subject approaching or moving away from the camera.
• A subject moving at a close distance to the camera.
• When shooting with a higher f/number.
• Also see "Shooting Conditions that Make Focusing Diffi cult" on = 146.
Since the lens is driven continuously and the battery power is consumed, the
o
possible movie recording time ( = 618) will be shortened.
With certain lenses, the mechanical sound for focusing may be recorded. In
o
this case, using Directional Stereo Microphone DM-E1 (sold separately) may
reduce such sounds in the movie.
Movie Servo AF will pause during zooming or magnifi ed view.
o
During movie recording, if a subject approaches or moves away or if the
o
camera is moved vertically or horizontally (panning), the recorded movie
image may momentarily expand or contract (change in image magnifi cation).
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