Scratching my head and a Eureka! moment…
So, I’ve been playing with my new Nikon D500 and one thing was a real head-scratcher: the behavior of focus vs. release priority mode when using continuous servo (AF-C) focus. For some reason, I couldn’t get focus priority mode to work when using AF-ON mode.
The priority mode option (in theory) allows you to choose as to whether or not the shutter will fire when the camera’s active AF sensor indicates proper focus. In single-servo mode (AF-S), focus-priority is the default. In continuous-servo mode, release-priority is the default.
I always set my Nikons to use AF-ON (back-button) focus, as I find this technique is quite useful to me (see my video tutorial on AF-ON focusing here). While 99.9% of the time I use (and recommend) using release priority with AF-C focus mode, there is one situation where focus priority makes sense, and that’s when you’re trying to make a focus trap, or shoot portraits with a relatively still subject. A focus trap allows you to set focus manually, hold down the shutter release, and then wait for the subject to cross the focus plane. When it does, it should trip the shutter release and be in focus. This technique can be useful when you’re trying to set up shots of moving subjects at specific locations in the scene.
When I put my D500 into focus-priority mode for AF-C, a funny thing happened. By funny thing, I mean nothing. I was able to release the shutter full blast just as if I were in release priority. That’s not what used to happen with my D3 bodies, so I was confused to the point of thinking it was a firmware glitch. And then I was playing around some more in the custom menus and discovered the clue… a little triangle next to one of the menu items in Custom Menu A8:
None of my other Nikons had this arrow before, so I hadn’t even noticed it. So, being the explorer I am, I bravely pressed the D-pad to the right. And behold:
There. It. Was. By choosing the “Disable” option, the camera no longer releases the shutter on out of focus shots when using AF-ON (back-button) focus and setting menu A1 to “Focus.” However, this setting did not seem to affect the Focus + Release and Release + Focus options; I guess those really only work when using the shutter release to activate focus drive <head scratch>. Nevertheless, now you know how to set up a focus trap on the D500 (and most likely the D5, too) by combining AF-ON focusing with focus priority release mode.