In this video we learn how to use the Mirror Lock Up on the Canon 40D. First, press the shutter and lock up the mirror. Second, press down on the exposure. Do this with a remote if you have one or use the timer mode. To do this, turn it out of focus then turn it on two or ten second focus. Then your single press will open it up and then take the exposure so you don't have to press it twice. This should make your exposure turn out correctly, use this whenever you would like and enjoy taking pictures!