 When the flash is attached directly to the camera—typically in a slot at the top of the camera (the flash shoe or hot shoe) or through a cable—activating the shutter on the camera triggers the flash, and the camera's internal light meter can help determine the duration of the flash.Accessories for cameras are mainly for care, protection, special effects and functions.In photography, the single-lens reflex camera (SLR) is provided with a mirror to redirect light from the picture taking lens to the viewfinder prior to releasing the shutter for composing and focusing an image.