Hi Warren. There are several ways of using the AF-On button on the F5 and F100. Here is one which have always used. With the camera mode set to manual exposure and AF set at continuous servo release priority, I am able to shift AF activation from the shutter release button to the AF-On button when changing the aperture through the sub-command dial. And when I am changing the shutter speed through the main command dial, I can shift AF activation back to the shutter release button. This way, I can continuously track a moving object and never lose AF. Another use, which I'm curently trying out with the new AF-S 80-200 f/2.8D is isolating the AF activation to the AF-On buttons only. The reason for this is the feature of the AF-S lenses which allows you to shift from AF to manual focus by just twisting the focus ring. Lifting off your finger from the shutter release button after manual override and depressing it again halfway re-activates AF. By isolating AF to the AF-onbuttons only, I can now manually override AF and even if I lift my finger off from the shutter release button, AF is not activated. Furthermore, by not pressing the AF-On button, AF is then in effect locked and can be only controlled manually. The sequence of operation then would be as follows: 1. activate AF by pressing AF-On button. Activate meter by pressing shutter button halfway. 2. fine tune focusing via manual override. 3. adjust aperture and/or shutter speed(lifting off finger from either AF-On button or shutter release button) 4. re-depress shutter release button to take picture. I hope this makes sense. Other people may find other ways of using this function. IMHO the ones I listed above are two good ones. Happy shooting. Carlo _________________________________________________________ DO YOU YAHOO!? Get your free @yahoo.com address at http://mail.yahoo.com
