A1 and A2 will decide whether or not your camera requires a focus lock before the shutter will trip, but you should find out why you are not getting a quick focus. Maybe a different choice of focus mode will work better. Or maybe there really is a problem. If you are shooting action or complicated scenes, your camera might be struggling to find focus with the mode you chose. There are two components to the focus settings. There are the focus area modes, like S, d9, d21, 3d, etc. This is how the camera identifies the focus point. Then there are the servo modes, af-s and af-c. This is how the motor behaves when a focus point is found. Af-s will focus on the point found and stop, af-c will keep focusing as things change. If menu A1 and A2 are set at the factory defaults, then focus choices combined with af-s will wait for focus before firing, if no focus then no shutter. Choices combined with af-c should fire instantly regardless of focus. Again, this is with menu A1-release, A2-focus. Try to figure out what is going on. I would start with A2 set to 'focus', af-s and single point. Try this on stationary simple subjects. Be sure the single point falls on your main subject. If that does not work, then you could have a problem.
