The Exposure Triangle

The Exposure Triangle is the term used to describe the way the exposure can be changed when you are taking a picture with a camera.

The three parts of this triangle are:

  • Shutter speed – How long the shutter stays open for the exposure,
  • Aperture – What size opening in the lens is made,
  • ISO – What the sensitivity the sensor is.

Since most cameras these days have an “Automatic Everything” mode, knowledge of the Exposure Triangle is usually not necessary to get a good exposure.  Modern cameras choose the “best” settings for each leg of the triangle and, more often than not, your picture is, as we say, properly exposed.

The purpose of this manuscript is to describe the effects of each leg of the Exposure Triangle on the resulting photograph.  These effects are broken down into

  • The primary effects,
  • The secondary effects, and
  • The tertiary effect.

Simply put, the primary effect of each leg of the exposure triangle is the exposure.  Each leg can make the resulting image lighter or darker.  The secondary effects of these legs are varied and, in my opinion, one of the more interesting aspects of the art of photography.  The tertiary effects are, in my opinion, a nuisance.

This web site

The content of this website is a manuscript on The Exposure Triangle.  You can jump to any part of it through this outline.


Next: Why the exposure “triangle”?

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