Tuesday, July 16, 2019

What is the diaphragm in the camera?

April 24, 2009 by  
Filed under Photo Technique


The diaphragm in the camera works in the same way that our eye. It opens and closes depending on the amount of ambient light.

In our eyes this mechanism is automatic and we don’t even realize it is there. Our eyes adapt quickly to new lighting conditions unless this change is dramatic and sudden. If we are in a dark room and we go outside to a very sunny and shiny day, we feel “blind” for a few seconds. This is because the opening in the iris called the pupil, opens in the dark and closes in the light.

This same principle was adapted for the camera lens. The diaphragm in the lens opens or closes depending on the amount of ambient light, this happens mechanically when we use the automatic settings in the camera. We can also set the aperture manually to control the amount of light that passes through the camera’s lens to the sensor or the film.

Until a few years ago this aperture was regulated with a ring in the lens. The new lenses use digital technology to set the aperture that is measure in “f/”.

f/2 – f/2.8 – f/4 – f/5.6 – f/8 – f/11 – f/16 – f/22 -f/32

The smaller number f/2 is the largest aperture and the larger number f/32 is the smallest aperture. Each step up allows half the light pass through the lens than the step before.

The aperture not only controls the amount of light, but also the depth of field.

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