How a camera works

Understanding how a camera works and how does a camera functions. Essentially, a camera is a dark box having a hole in one end covered by a glass lens. Either inside the lens, or in the back of it is a shielding device called a shutter. At the back of the box is a piece of photodiode sensors on which image/light is received before it is translated to digital signal.


The purpose of the shutter is, first of all, to keep the inside of the box in pitch darkness so that no light reaches the sensor. The only time the shutter is open is when an exposure is being made.


This is what happen when the lever on the outside of the camera is tripped for making an instantaneous exposure:

  1. The shutter opens to permit light to enter the camera.

  2. Rays of light reflected by the subject pass through the lens and through a circular opening called a diaphragm on their way to the sensor.

  3. The shutter closes automatically.

In the fraction of a second that elapses between the opening and closing of the shutter, the "working heart" of the camera does its job. The shutter controls "how long" the light will be permitted to enter the camera. The diaphragm opening controls "how much" light will be allowed to enter during the given interval of time. The lens bends the rays of light so that the light reaches the sensor of the camera.


The interaction between the shutter, diaphragm, lens and sensor can be comparable to the way our human eye functions.


Lens functions as the human eye's pupil. It controls the opening through which light rays enter.


Diaphragm functions as human eye's iris. It is mainly about the opening which control "how much" light can enter during a given interval of time


Shutter functions as human eye's eye lid in which it keeps the interior dark when closed and also controls how long light can enter during an exposure.


Sensors is like our human eye's retina where all the light rays are recorded to show their impressions.

Things that you should know about camera photography


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