(User’s Manual: D300S page 48; D300 page 79)
Live view mode allows you to use the Monitor on the back of your camera to frame pictures instead of using the eyepiece and Viewfinder. It has two modes, Hand-held and Tripod, each of which uses a different type of autofocus (AF). Hand-held mode uses phase-detection AF, while Tripod mode uses contrast-detect AF. We’ll discuss this more in a moment.
To use Live view mode, simply press the tiny Lv button on the back of the camera, just above the AF-area mode selector. The Monitor will turn on and show you what your camera’s lens sees. It’s like using the Viewfinder, but much larger.
Live view mode is an approach that some consider a throwback and others a lifesaver. Why do I say that?