If the iPad is locked, there’s a shortcut to quickly open the Camera app straight away. Swipe from right to left across the lock screen until the Camera app appears. Bear in mind you can’t return to the lock screen by swiping back the other way – you’ll need to press the Home button instead.
For added security, users aren’t able to look through camera roll items, or see past photo history beyond what has just been taken if the passcode was enabled when the Camera app was opened via this method.