12.5. Custom Functions

In Chapter 9, you got a glimpse of the T1i's custom functions when I discussed mirror lockup. Custom functions are special commands that you access through the Custom Functions command on the third tool menu. Although a few of these commands, such as Mirror Lockup, seem more like primary commands that should be in the normal menu system, the bulk of the custom functions are commands that let you tweak and alter the behavior of other commands.

To alter a custom function, choose custom function (C. Fn) from the third tool menu. Use the left and right arrows to select the function you want to edit, and then click Set. You can then use the up and down arrows to change the value of that function. Press Set when you've configured it as you want it. Here's what they do: