Nikon D300S - Focus Lock

Focus Lock
Focus lock can be used to change the composition after focusing,
making
it possible to focus on a subject that will not be in a focus
point in the final composition. It can also be used when the
autofocus system is unable to focus (CD 82).
1 Focus.
Position the subject in the selected focus
point and press the shutter-release
button halfway to initiate focus.
8
.
1
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I "
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2 Check that the in-focus indicator
(e) appears in the viewfinder.
80
Single-servo AF
Focus will lock automatically
when the in-focus indicator I Jjt=
appears, and remain locked
until you remove your finger
from
the shutter- re I ease L--~L---I_--L",----L---'--J
button. Focus can also be locked by pressing the AE-UAF-L
button (see following page).
B Shutter-Release Button AE-L
If On is selected for Custom Setting c1 (Shutter-release button
AE-L; CD 273), exposure will lock when the shutter-release button is
pressed halfway.