Canon EOS Rebel T6i EF-S 18-55mm IS STM Lens Kit Instruction Manual - Page 154

f: Changing the Depth of Field D Using the Built-in Flash To obtain a correct flash exposure, the flash output will be set automatically to match the set aperture (autoflash exposure). The shutter speed will be set automatically between 1/200 sec. - 30 sec. to suit the scene's brightness. In low light, the main subject is exposed with the auto flash metering, and the background is exposed with a slow shutter speed set automatically. Both the subject and background look properly exposed with a touch of atmosphere (automatic slow-speed flash sync). If you are handholding the camera, keep it steady to prevent camera shake. Using a tripod is recommended. To prevent a slow shutter speed, under [z1: Flash control], set [Flash sync. speed in Av mode] to [1/200-1/60sec. auto] or [1/200 sec. (fixed)] (p.174). Depth-of-Field PreviewK 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). While looking at the Live View image (p.192) and holding down the depth-offield preview button, you can see how the range of acceptable focus will change as you adjust the aperture. 154