HP Jornada 520 User Manual page 22

If the digital viewfinder is running, other applications on your HP
Jornada may run slowly. Change to Review mode or exit the HP pocket
camera software to speed up the other applications.
To take a picture while you are running another application, first check
that the LED ring on the camera shines steady green. If the LED is
blinking slowly, press the shutter button on the camera once to wake
the camera from Standby mode. Press the shutter button again to take
a picture.
18 hp pocket camera