The family of angles in underwater photography

Due to its' specific physical properties, water bends, filters, difracts, refracts, diffuses and, in general, globally perverts the light we are used to see on the surface. It is therefore necessary to use artificial lighting in order to photograph most underwater subjects. When using such lighting, we begin to manipulate the properties on subjects in ways we are not normally used to: in photographing landscapes, for example, one hardly manipulates the light falling upon the landscape: the lighting in the photograph will depend on the position of the sun and the presence, or absence of clouds, etc, all factors that cannot (yet) be handled. So if we are, in underwater photography, using artificial light sources that replace the play of the sun and the sky and the clouds upon the subjects, we should understand better how those light sources affect the way we see the objects and, therefore, the way they will affect the way the photograph is going to "happen".

Light is important by itself, by the way it affects the subject and by the way it is affected by the subject.

By itself, light is important for photography in terms of brightness, color and contrast.

Light can also affect the subject by being transmitted (going through) the subject in either a direct way (e.g. through glass) or in a diffuse way (e.g. any translucent material), or by being absorbed by the subject, therefore being transformed into other form of energy (heat).

Light can be affected by the subject. It can be reflected, in different ways, by it. It is the reflection of light on a subject that makes it visible and photographable.

Underwater, transmission and absorbtion are relevant factors that change the quality and quantity of light available, but reflection is the key to the quality of a photograph.

Taking reflection into account, there are a few rules for lighting any subject:

(a) The effective size of the light source is of the foremost importance when lighting a photograph. It is the size of the light source that determines what type of shadows are produced and may affect the type of reflection. A small light source (or a light source that is very close to the subject) will produce hard shadows and high contrast (direct reflection). A large light source will produce soft shadows and low contrast (diffuse reflection)

(b) In theory, there are three types of reflection possible in a given surface (diffuse, direct or glare). In practice, all subjects have a mixture of the 3 in different proportions. The proportions of each reflection of a subject will determine the way the surfaces look.

(c) Some of these reflections only occur when light strikes the surface from within a limited family of angles. After deciding which types of reflection are important in a given situation, this "family of angles" can determine where the light is supposed to be, relative to the subject.

A photographer should be an editor of the image before shooting it, because our brain can edit a scene but cannot edit a photograph of the same scene.



Light Science & Magic - An Introduction to Photographic Lighting
Fil Hunter and Paul Fuqua