I have my D300 set up so that I use the AF-ON button for focus only. I was just wondering about something I noticed the other day shooting. When I push the AF-ON button and release...I can then recompose and shoot, right? The main question is in the viewfinder...the "dot" that tells you when things are in focus comes on when I hit the button, but when I release it the "Dot" goes away. Does this mean that the focus is indeed NOT locked on target? Should the dot stay on even after I release the AF-ON button? I may have missed a setting when I set this up. The thread on the AF-ON button is where I learned of this.