Canon AF514XL-S - Manual (Page 72)

In these cases, using the instant focus lock button on
the main subject may not help. Please see the
next page for recommended ways to focus in these
cases.
3. Two or more subjects at
different distances fall
within the autofocus circle
at the same time.
Others:
a) The subject Is very glossy
or has bright light behind it,
such as a glossy car or
telephone
or a subject
which is backlit by the sun.
b) The subject has only one
pattern, such as a tile roof.
c) The subject is composed of
very small, uniform parts,
such as a patch of grass or
a bed of very small flowers.
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