FE (flash Exposure) lock is the flash version of AE lock. With the 420EX attached tot he camera, the camera's AE lock button becomes the FE lock button. With FE lock you can lock the correct flash exposure reading for any part of the picture.
- Set the cameras command dial to a Creative Zone mode
- Focus the subject
- Press the shutter button halfway
3. Aim the center focusing on the subject where you want to lock the flash exposure reading, then press the * button
- In the viewfinder the * icon is displayed
- The 420EX fires a preflash and the required flash exposure is locked.
- In the viewfinder the <FEL> is displayed for 0.5 sec.
- Each time you press the * button, a preflash is fired to obtain the correct flash exposure which is then locked
- FE lock is canceled when the icon turns off or when the command dial is turned.