The incident meter is aimed at the light source and measures the light source falling directly on a scene and is not influenced by the reflectance of the subject being photographed. For more precise control of the photograph, incident meters are also used to measure various levels of light from multiple sources falling on separate parts of a scene.
Using Incident Meters
Incident metering measures the intensity of light falling on the subject and gives accurate and consistent rendition of the tonality and contrast regardless of reflectance, background, color, and shape. Subjects that appear lighter than gray will appear lighter. Subjects that are darker than gray will appear darker. Colors will be rendered accurately. Highlight and shadow areas will fall naturally into place. This handheld meter shows you how much light is falling on the subject you want to photograph. The meter's sensor is found under a small white dome that resembles half of a ping-pong ball. The face of the meter has a dial that you can adjust according to your camera's film sensitivity or sensor power. The meter then displays a reading that you can use to set your camera's shutter speed (how fast the picture will be taken) and aperture (the size of the lens opening that lets the light into the camera). Incident meters are also called "spot" meters because they measures the light in a particular part of the image, not the whole scene at once.