FE lock is simply obtaining a proper flash exposure, pushing the right button to lock in that exposure.
就是先获得恰当的闪光曝光值，压下闪光曝光锁按钮，锁定这个曝光值。
2
To make this work, use the partial metering mode (or spot metering mode) over the subject where you want to lock the flash output then press the asterisk (*) button.
相机的测光方式要设置在局部测光或点测光方式，测光点对着你想要锁定曝光值的目标，按下锁定钮。
3
The speedlight will pre-flash that area and lock that exposure into memory. I might caution you that you have 16 seconds to then recompose and take the shot.