Almost every photographer in the world has heard of the “Exposure Triangle”, the Holy Grail of understanding how to properly use your camera with manual controls. It is this arcane knowledge that is purported to separate the Neophytes from the Masters. But, there is a fundamental problem with how we illustrate this “Trinity”.
Article and Photos by Stuart Blower © 2024
Your “Basic Camera Tool Kit” includes 3 things, shutter speed, aperture opening and ISO sensitively, you would not be blamed for thinking a triangle will provide the necessary visual elements that will make everything clear. You would be wrong.
Yes, it is true that a properly constructed triangle graphic, can illustrate you how to move around the perimeter of the triangle either clockwise or counter clock wise, in order to pick numbers of shutter speed and aperture, that will increase or decrease the amount of light you work with. However the ultimate truth of working with this exposure trinity is still not revealed.
Enter the “Exposure Quadrangle”, a simple graphic designed to reveal everything you need to know about setting the correct exposure.
What is the secret you ask?. Simply put, throw away the Triangle and imagine a Teeter Totter. One end is the shutter speed and the other end is balanced by the Aperture. When one side goes up (higher speeds, less light) the other side goes down (lower aperture numbers, more light). This is a reciprocal relationship.
It now easy to see, that selecting a higher Sutter Speed in order to freeze the action forces the Aperture to be at a lower number with less depth of field.
Where does the third component fit in? Imagine the centre post that holds the balanced bar. This is the graphic representation of ISO ( light sensitively )
Raise the post and increase your light sensitively (higher number) . Lower the post and lower your light sensitively (lower number). The balance bar still provides the working relationship of the shutter and aperture with the added benefit of raising or lowering your ISO needs to match lighting conditions.
An understanding of the interplay of these three “Basic Camera Tool Kit” elements and your ability to manipulate them, is a major step in your photography journey.