I just returned from Miami teaching a lighting class with Dave Tejada for the Mentor Series. We had a blast; South Beach is always a fun place to photograph people. This class focused on using speedlights, and using flash off-camera. One way to shoot flash off-camera is using a SU800 transmitter. Another way is turning your pop-up flash into a commander, and controlling the flash by using menus on your LCD. But a more efficient way to access the commander menu (instead of scrolling through multiple windows) is to assign your AE-L/AF-L to this function. With a one button push you can access your commander mode to adjust your speedlight output. Here’s how (for the D810; should be similar for other cameras):
Now, when you hit the AE-L/AF-L button, the commander mode pops up on your LCD allowing you quick control of your off-camera speedlights. You still only get two groups (versus three with the SU800), but being able to use your pop-up flash is very convenient and a great backup if you loose your SU800.