Canon POWERSHOT SD400 DIGITAL ELPH User Manual page 92

It may be difficult to focus on the following types of subjects. Usethe focus
lock or AF lock in these situations.
Subjects with extremely low contrast to the surroundings
Scenes with a mixture of near and far subjects.
Subjects with extremely bright objects at the center of the composition
Subjects that are moving quickly
Subjects through glass:
Try to shoot as close to the glass as possible to reducethe chances of
light reflecting back off the glass.
Shootingwith the FocusLock
The focus lock can be used in any shooting mode.
Aim the cameraso thatan objectat
thesamefocal distanceas the main
subjectis centeredin the
viewfinderor in the AF frame
displayed on the LCDmonitor.
Presstheshutterbutton halfway
(two beepswill play).
The focal d istance t otheobject i slocked.
Re-aim thecamerato composethe
shotas desired and pressthe
shutterbutton fully.
9O