By Petr Carter, Blake Murrell, Troy Prather, and Eric Hempelmen

Light meter is a device used to measure amount of light in places needed.

They are used often in photography to determine proper exposure for a photograph.

It also used in fields of cinematography and scenic design, in order to determine the optimum light level for a scene. Many used in the general field of lighting, where they can help to reduce the amount of waste light used in the home, light pollution outdoors, and plant growing to ensure proper light levels.

Accurate exposure is affected by the intensity of light striking the film and the length of time the shutter is open. Light intensity is affected by the lens opening (T-stop), the amount of light falling on the scene (incident light), and the strength of light reflected off the subjects (scene reflectance).

Measuring the amount of light in a scene helps the cinematographer select the camera settings that will best satisfy the creative intent.

Photometry focuses on assigning numerical values to light energy emitted from wavelengths between 400nm and 700nm. This is the visible light portion.

A subject called Radiometry focuses of most of the EM spectrum (400nm to 1000nm).

This light meter from Quantum Instruments is just for Photometry use.

Think of this value as what Amps or Volts is to electricity.

45 Fc in bathroom 36 Fc in 3rd floor hallway 12 Fc at top of stairs, 8 at bottom 55 Fc in Library 27 Fc on 2nd floor hallway, old building 24 Fc in old building bathroom .3 Fc in a locker 58 Fc in big gym Off the scale anywhere outside 5 Fc in old building stairwell 100 Fc near window in old building 63 Fc in old building classroom 65 Fc in basement hallway