Canon EOS 70D Operation Manual - Page 163

f: Aperture-Priority AE If the "30"" shutter speed blinks, it indicates underexposure. Turn the dial to set a larger aperture (lower f/ number) until the shutter speed blinking stops or set a higher ISO speed. If the "8000"" shutter speed blinks, it indicates overexposure. Turn the dial to set a smaller aperture (higher aperture f/number) until the shutter speed blinking stops or set a lower ISO speed. Aperture Display The higher the f/number, the smaller the aperture opening will be. The apertures displayed will differ depending on the lens. If no lens is attached to the camera, "00" will be displayed for the aperture. Depth-of-Field PreviewN The aperture opening (diaphragm) changes only at the moment when the picture is taken. Otherwise, the aperture remains fully open. Therefore, when you look at the scene through the viewfinder or on the LCD monitor, the depth of field will look narrow. Press the depth-of-field preview button to stop down the lens to the current aperture setting and check the depth of field (range of acceptable focus). A higher f/number will make more of the foreground and background fall within acceptable focus. However, the viewfinder will look darker. The depth-of-field effect can be clearly seen on the Live View image as you change the aperture and press the depth-of-field preview button (p.216). The exposure will be locked (AE lock) while the depth-of-field preview button is pressed. 163