Canon 150U - Manual (Page 8)

O Subjects Difficult to Autofocus
The green lamp may blink 4 times per second for subjects with the
following characteristics that cannot be brought into focus.
In situations like this, focus on something roughly the same distance away
as your subject and lock the focus for the shot.
Main types of subjects where focusing is difficult:
• Subjects in scenes without much contrast, ë.gi blue sky.’^or scenes bf
Plainly one cblor
• Subjects in very dark places ^ '
• Subjects in extreme backlit situations or subjects which are extremely
reflective, e;gT the body of a car^which^ÿves off a strong reflection .
• Subjects in a pHotograph;* some of which are close and sòme of vyhich
are in the distance; e.g. animals in a cage
• Subjects with a repetitive pattern, e.g. continuous windows in a
building,¡etc..