f: Changing the Depth of Field108To obtain a correct flash exposure, the flash output will be setautomatically to match the set aperture (autoflash exposure). Theshutter speed will be set automatically between 1/200 sec. - 30 sec. tosuit 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 setautomatically. Both the subject and background look properly exposed(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 [53: Custom Functions(C.Fn)], set [3: Flash sync. speed in Av mode] to [1: 1/200-1/60 sec.auto] or [2: 1/200 sec. (fixed)] (p.259).The aperture opening (diaphragm) changes only at the moment whenthe picture is taken. Otherwise, the aperture remains fully open.Therefore, when you look at the scene through the viewfinder or on theLCD monitor, the depth of field will look narrow. With the procedurebelow, you can check the depth of field before taking the picture.1 Enable depth-of-field preview to be used.Under [53: Custom Functions (C.Fn)], set [9: Assign SETbutton] to [4: Depth-of-field preview] (p.264).For details about Custom Function settings, see page 256.2 Exit the menu.Press the <M> button two times to exit the menu.3 Press the <0> button.X The aperture will be stopped down so you can see the depth offield.D Using the Built-in Flash3 Depth of Field PreviewNWhile looking at the Live View image (p.134) and holding down the <0>button, you can change the aperture and see how the depth of field changes.
