The D200 product manual states: (Regarding the AF-ON Button) "For the purpose of focusing the camera, pressing the AFON button has the same effect as pressing the shutter-release button halfway."
I have been told that pressing (and releasing) the AF-ON button will allow you to focus continually frame after frame, but the manual leads me to believe I must press and hold the button while pressing the shutter release button. Then, next shot do that all over again. Can some one tell me the proper use of the AF-ON button? Also, how do I use this AF-ON button for shooting an HDR sequence?