Pentax K-5 Operating Manual page 135

Setting the Auto Power Off Function
You can set the camera to turn off automatically if unused after a certain
length of time. Select from [lmin.] (default setting), [3min.], [5min.],
[10min.], [30min.] or [Off].
Set in [Auto Power Off] of the ['& Set-up 3]
menu (p.279).
• The Auto Power Off function does not work in the following situations.
- when the Live View image is displayed
- when the slideshow is played back
- when the camera _sconnected to a computer with an USB cable
• If the camera turns off after the set length of time, perform one of the following
operations to reactivate it....
- Turn on the camera again.
- Press the shutter release button halfway.
- Press the r-€l button. MENU button or INFO button.