I recently purchased a Nikon D810. I use back button focusing all the time, mostly single servo (AF-S Single), where the AF-ON button serves as my button to get focus, and then I fire the shutter away to take a photo. When shooting outdoor portraiture, this setup is fine as natural light changes so often I need to lock focus on the subject's eye time and time again and recompose quite often, especially when shooting a shallow depth of field at f/1.4 or f/1.8, etc. However, in studio, I'm often shooting at f/10 where subtle changes in lateral position won't really affect the focus on a subject in the same focal plane. So I typically lock focus once, then switch the button near the lens from Auto Focus to Manual, and then fire away shot after shot so I don't have to lock focus for every shot even if the subject moves slightly away from the Single-Servo focus point. Is this the norm? Unlike my original D750, the D810 has both an "AE-L/AF-L" and "AF-ON" button on the back. Is there a way to use the "AE-L/AF-L" to lock and hold focus, so that I can just fire away? (Menus only show a "lock and hold" for exposure with this button and not for focus. Hmmm.) Just wondering if I'm doing this right, or (most likely) if there's a better way that I'm not doing when shooting in-studio. Maybe people in studio use a focus group instead of AF-S Single? I'm pretty sure I'm not doing it the ideal way. Any help is appreciated, thanks.