those were the good days of our "idiot proof" 35mm p&s and the "old shool" SLRs!! the newer AF digital cams, SLRs, and DLSR usually employ some form of autofocus before capturing / triggering, unless you are able to bypass this with a manual (M) focus mode. short of which, normally an immediate full press on a AF camera would not lead to an immediate trigger, as the cam would attempt to focus (similar to that of a half-press) first before firing as soon a focus is achieved (else not at all).