How to properly use Focus in First Person?

If your camera is locked in the first person does your camera need to focus on the character or in the direction the camera is facing?

To clarify (and this is not how it should look) I mean something like this:

Camera focus on the character: game.workspace.CurrentCamera.focus = localplayer.Character.HumanoidRootPart.Position

Camera focus in camera direction: game.workspace.CurrentCamera.focus = CFrame.new(HumanoidRootPart, lookvector of Character)

Also whenever you begin to type focus you get 2 alternatives: "focus" and "Focus". The only difference is that one of them starts with a capital letter. Is there any difference in function?