Fill-in flash photography in Av mode with EOS cameras utilizing A-TTL, E-TTL and TTL with either EZ or EX type of Canon Speedlites, will provide the required depth-of field coverage for your pictures. Fill-n flash in Av mode can be used in both outdoor and indoor situations but is more effective when the surrounding conditions are bright enough to ensure the shutter speed selected by the camera is able to compensate for handheld shooting. Used indoors with low light conditions, the camera will select a shutter speed that will allow correct ambient exposure in the background but with a risk of camera shake since the setting can be as slow as 1/8 sec and lower. Av fill-flash mode can be used to deliberately control the amount of shallow focus for your pictures, as shown in the final photo below. Fill-in Flash photography with Aperture-priority AE E-TTL flash with Speedlite 380EX, at f/4 TTL flash with Speedlite 540EZ, at f/1.8 TTL flash with Speedlite 540EZ, at f/3.5 TTL flash with Speedlite 540EZ, at f/2.0 Text and photos by Philip Chong. Copyright 1999 by Canon Marketing (M) Sdn Bhd << Back to Main . 1 . 2 . 3 . 4 . 5 .