Canon EF 400mm f/2.8L IS USM Instructions Manual page 11

7. Tips on Using the Image Stabilizer
The image stabilizer for this lens is effective for hand-held shots in the following conditions.
●
MODE 1
ON
●
In semi-darkened areas such as indoors or
outdoors at night.
●
In locations where flash photography is
prohibited, such as art museums and theater
stages.
●
In situations where your footing is uncertain.
●
In situations where fast shutter settings
cannot be used.
OFF
●
MODE 2
ON
●
When panning subjects in motion.
OFF
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