In photography, meter is a device which is generally used to calculate the quantity of light. It helps to measure the intensity of light in a given situation, which leads to the proper calculation of diaphragm aperture and shutter speed. Typically there are three major types of meters which are used in photography. These are incident/flash light, reflected light and spot.

Incident/Flash Light Meter

Incident/flash light meter is used when the intensity of the light falling on the object is to be measured. Flash meters measure the light emitted only for a split second, using strobe units.

Reflected Light Meter

Reflected light meter is mainly used when the intensity of the light reflected by the object is to be measured. For many years, the reflected light method was important and famous among photographers, whether professional or amateur. But soon they came to realize that whenever the object was mainly either dark or light, the exposures based on reflected light were generally inaccurate. Even though these errors were not very prominent in black and white pictures but they had a disastrous effect on colored photography.

Spot Light Meter

Spot light meter is used when the light-reflect on the area of one degree is to be measured. The most popular type of reflect type meter is the one degree spot meter which has the ability to reach out and detain its reading to central objects at a distance from the camera. Whether there is a figure on stage or children in the park or the speaker at a news conference, the only way to meter a distant object perfectly if the surrounding in ambiguous, , is to use spot meter.

The simplest meter consists of photoelectric cell that produces a tiny electric current when it is exposed to light and moves a needle on the scale. There is an adjustable dial on the meter which indicates the film speed. When the dial is arranged in line with the needle/pointer, the meter shows various arrangements on diaphragm aperture and shutter speed which will generate equivalent exposures, and thus the camera can be set accordingly.

There are certain meters in which photoconductive cadmium sulfide cell is used as the light receptive element. This cadmium sulfide cell is exceedingly sensitive even in low light situations. In late 1980’s, there was an innovation in which silicon diodes where used as light sensitive element instead of cadmium sulfide cells. Meters outfitted with these are even better sensitivity than cadmium sulfide cells.

A particular meter is used for studio photography that records the color temperature of light. Different types of lights have their own particular color temperature and different wavelengths of light respond to specific temperature (expressed in Kelvin-K). Color temperature meters records the precise color temperature of any light source. It then suggests the most suitable correction filters to balance the color with the film type set on the meter. For still photography, the finest meter to use is the three color temperature meter. When professional photography is done indoor where there is artificial lightning color temperature meter becomes very important because color temperature of incandescent and fluorescent bulbs differ from manufacturer to manufacturer and the color can also change with the aging of the bulbs.

After discussing the meters, it is necessary to put some light on the metering modes. In photography metering modes are the ways in which a camera determines the correct exposure. Camera generally allows the person to select one of the three kinds of metering mode. They are spot, center- weighted average or multi-zone metering modes

Spot metering mode allows the camera to measure a very small area of the scene, typically the focal point of the scene.

In center weighted average metering, the meter focuses between 60 – 80 % of the sensitivity towards the vital part of the scene.

Multi-zone metering which is also known as matrix metering, measures the light intensity in numerous points in the scene.