Reflected light is returned to the observer after striking surfaces such as water, photographers' reflectors or light-coloured walls. It is often modified by the reflecting surface and may be polarized, diffused or changed in colour. It has many implications in available light photography.
When light falls directly onto one side of a person or object, the other side will be in shadow. However, if the subject is close to a reflecting surface the shadows will be filled to some extent by reflected light. Snow and sand reflect light in a similar manner and can be used to fill shadows from beneath a subject. More light is returned from the reflecting surface when it is directly lit. Less is reflected when the source is indirect or diffused.
Reflected light can also cause significant problems. It can conceal detail behind transparent reflecting surfaces, such as spectacles, and cause sufficient glare to mask brilliant colours. In portraiture, particular difficulties arise when light is reflected from skin or eyes.
Skin can be extremely reflective, and highlights may be sufficiently bright to be considered specular. The sun striking the forehead, the tip of the nose or wet lips produces highlights that can be a problem. Studio models have the option of using a light dusting of translucent powder to produce a smooth mat skin texture, but for most other situations and subjects such precautions are not possible.
The human face is an extraordinarily eloquent guide to personality, and the eyes are its most recognizable and important features. Consequently, they demand and deserve special attention. The surface of an eye is smooth, moist and mirror-like. Primary highlights add vitality but other reflections may dilute the intensity of eye contact. It is not unusual to see a reflection of photographer, camera and tripod in the eyes of a subject. This is not easy to control but should be avoided wherever possible.
Similar effects are sometimes produced by fill-flash. The affected areas can be large and the degree of overexposure quite pronounced, so dealing with them in a traditional darkroom may not be possible. It can be beneficial to diffuse flash output by covering the head with a small softbox or a couple of layers of white handkerchief. The output is consequently increased by the electronics of course, but the problems of reflection are often less pronounced.