What the viewfinder indicators mean on a PowerShot A550, A560 and A570 IS.
The indicators light or blink when the <ON/OFF> button or the shutter button is pressed.
Upper Indicator
Green: Ready to shoot (camera beeps twice)
Blinking Green: Image recording/reading/erasing/transferring (when connected to a computer)
Orange: Ready to record (flash on)
Blinking Orange: Ready to record (camera shake warning), charging flash
Lower Indicator
Yellow: Macro mode/Manual focus mode/AF lock mode
Flashing Yellow (camera beeps once): Focusing difficulty (although you can press the shutter button, try using focus lock or adjust the focus manually).