A photometer measures the intensity of light.
A photometer is a device used for measuring the intensity of light . The term is formed with the compositional elements photo- (referring to light ) and ‒́meter (referring to measurement or a device used to measure ).
Before continuing, it is important to note that, in the field of physics , light is called the electromagnetic wave that is recorded in the visible spectrum (that is, in the area of electromagnetic radiation that can be perceived by the human eye). human). The idea of intensity , meanwhile, refers to a level of force.
How a photometer works
The photometer is a device that measures the number of photons present in a beam of light. At this point it must be clarified that photons are the elementary particles that, according to the criteria of quantum physics, make up electromagnetic radiation .
What the photometer does is analyze the light that its photosensitive cell receives. These instruments were invented at the end of the 19th century in England , replacing the measurement of light that was carried out through the use of chemicals.
Depending on their characteristics, photometers can measure incident light (calculating the level of light that reaches an object) or reflected light (that is, the light reflected by the objects themselves). Both are important in the field of photography .
Light meters are very important in photography.
Its use in photography
To measure the light that exists in an environment or on a stage, the photometer is essential. Thanks to the photometer you can calculate the correct exposure and thus take the best photographs.
Currently, cameras have an internal photometer that performs this task . However, when at a professional level they want to work with the greatest possible accuracy, photographers usually resort to an external photometer or handheld photometer .
In many cases, a very precise photometer is needed for optimal image registration. When the lighting is poor, there are marked contrasts, there are several lights incident simultaneously or a white background is detected, photometers are necessary to measure the light precisely and promote the appropriate adjustment.
The photometer in astronomy
Astronomy is the science that studies the laws, movements and characteristics of the stars (celestial bodies). Those celestial bodies that, at night, can be seen for their brightness are called stars .
Since photometers are used to evaluate the intensity of the radiation emitted by an object, in astronomy these devices make it possible to measure the brightness of stars . Specifically, they usually transform the light they receive into an electrical signal.
Photometers are generally installed in the focal plane of a telescope . In this way, they can measure the light that arrives from the stars. Today, in any case, CMOS or CCD sensors are usually used to fulfill that same function.