Fill flash is a photographic technique used to brighten deep shadow areas, typically outdoors on sunny days, though the technique is useful any time the background is significantly brighter than the subject of the photograph, particularly in backlit subjects. To use fill flash, the aperture and shutter speed are adjusted to correctly expose the background, and the flash is fired to lighten the foreground.
Most point and shoot cameras include a fill flash mode that forces the flash to fire, even in bright light.
Depending on the distance to the subject, using the full power of the flash may greatly overexpose the subject especially at close range. Certain cameras allow the level of flash to be manually adjusted e.g. 1/3, 1/2, or 1/8 power, so that both the foreground and background are correctly exposed, or allow an automatic flash exposure compensation.
Papilio xuthus, also known as the Asian Swallowtail, Chinese Yellow Swallowtail, or as the Xuthus swallowtail, is a middle to large sized swallowtail butterfly found in northeast Asia, Korea, Japan, and Hawaii.