SteveR wrote:
There is also a selection, I can't tell you what the custom setting is, related to focus. You have three choices: 1, the shutter will release whenever the shutter button is pushed; 2, the shutter will release when focus is close to perfect; 3, the shutter will release only in perfect focus. If 2 or 3 are selected, you may get varying degrees of delay if you're not in focus when the shutter button is pushed.
It's Custom Setting a1/a2 for AF-C/AF-S. The D7100 only has release or focus priority for both, for when the shutter release is pressed or when focus is locked. The D800 adds release+focus priority for AF-C.