Does turning the display of manually save it?
I mean when you keep your finger down on F1 - does this actually turn off the display or what?
I'm confused by this- there are two different questions here. what are you actually asking? what does "save it" mean? Do you mean battery life, or actual life of the monitor?
I'm going to guess you're trying to ask if it saves battery life, and the answer is "yes," but not nearly as much as if you, say, turned off wireless connectivity - airport sucks battery life way down.