essential skills: photographic lighting
Intensity Light intensity is a description of the level of a light’s brightness. The intensity of light falling on a subject can be measured using a light meter. This is called an ‘incident reading’. A light meter built into a camera does not directly measure the intensity of light falling on the subject but the level of light reflected from it. This is called a ‘reflected reading’.
Mark Galer
Reflectance Regardless of the intensity of the light falling on the subject different levels of light will be reflected from the subject. The amount of light reflecting from a surface is called ‘subject reflectance’. The levels of reflectance vary according to the color, texture and angle of the light to the subject. A white shirt will reflect more light than a black dress. A sheet of rusty metal will reflect less light than a mirror. In all cases the level of reflectance is directly proportional to the viewpoint of the camera. If the viewpoint of the camera is equal to the angle of the light to the subject the reflectance level will be greater. The level of reflected light is therefore determined by: ~ ~ ~ ~
Reflectance of the subject. Intensity of the light source. Angle of viewpoint and light to subject. Distance of the light source from the subject.
Although the intensity of the light source may remain constant (such as on a sunny day) the level of reflected light may vary.
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