Lux meters measure the intensity of light.
A lux is a metric unit of measurement that represents the intensity of light. Lux meters, also called light meters, measure the lux of the light falling on a specific object.
Uses
Lux meters are most commonly used by photographers and cinematographers to determine the intensity of the light falling on a photographic subject. The photographer uses the lux reading to determine the camera's aperture and exposure settings.
Types
There are two main types of lux meters: reflected-light meters and incident-light meters. Reflected-light meters are situated near or in the camera itself and measure the intensity of the light reflected from the subject to the camera. Incident-light meters are situated as close to the subject as possible and measure the intensity of the light falling on the subject.
Reflected-Light Meters
These are commonly installed in consumer products like camcorders or point-and-shoot cameras. They work well for scenes in which light is relatively evenly distributed, since the readings they take are of the general light intensity in the scene. Scenes containing objects whose brightness varies greatly (such as sunsets) will generally not be properly exposed when using readings from reflected-light meters. Nevertheless, reflected-light meters are useful when shooting subjects the photographer is not at leisure to pose and measure.
Incident-Light Meters
These are always separate devices and generally used by serious film photographers. During measurement, they are held in front of the subject with their light receptor facing the camera. A photographer may measure the intensity of the light falling on several subjects in a scene before deciding set the camera.
Possible Obsolescence
While incident-light meters are essential for professional film photography, they are considerably less necessary in digital photography. Because it is easy and free to take a test shot with a digital camera, one that can be immediately examined, a digital photographer can use a camera's reflected-light meter for a base reading, make a test shot and adjust the exposure based on the results.
Tags: intensity light, light falling, measure intensity, measure intensity light, intensity light falling, reflected-light meters, incident-light meters