Canon EOS 40D: Auto Exposure Lock

Video Transcript

"All right, let's talk about auto exposure lock, or AE lock on your Canon 40D. The auto exposure button is on the back side of the camera next to the focusing point button. The focusing point button is the button on the farthest to the right of the camera and the next button over has a little asterisk or a star, and that button is the AE lock button. You'll use this function when your focusing area is different from your light metering area. Let's say that I wanted to take a shot of a plant but I wanted to take the light metering from a different part of the room. So I'm going to take my light metering from this area of the room by holding down the shutter button. That's going to give me an exposure, and what I want to do is while I'm holding down the shutter button, I'm going press the AE lock button, which is the star. I'm going to hold down the shutter button and press the AE lock button. And that locks my exposure, so the exposure is going to stay the same, and I'm going to recompose the shot, and then take the picture. That will give me the exposure settings that I had set before I recomposed the shot. If I wanted to take multiple shots with the same exposure settings, all I need to do is hold down that exposure lock button and keep taking several shots. And that will give me several shots with the exact same exposure setting. Soon as I let go of the exposure lock button, I can play through those images. But exposure is essentially locking your aperture and shutter settings to keep the exposure at the same amount."