Understanding the exposure triangle is one of the fundamental principles that is vital to getting a good grasp of photography and building a solid foundation in it.
It forms a big step in breaking away from shooting in auto mode, and means the photographer is in full control of how a shot will look, rather than relying on the camera to figure it out.
The exposure triangle is relatively easy to understand in concept, but truly understanding it and how each part relates to the other is what will take practice and experimentation.
In simple terms, the exposure triangle is the relationship between the three main elements on your camera.
It is the relationship between the amount of light allowed to enter the camera, the amount of time light is allowed to enter the camera, and the amount of sensitivity of light due to the film or digital sensor of the camera.
In technical terms, the amount of light is controlled by the aperture, the amount of time is controlled by the shutter speed, and the sensitivity is determined by the ISO.
In auto mode, changing any one of this exposure triangle means that to gain the same standard shot, one or both of the other two will also need to change.
One of the most common analogies in understanding the exposure triangle is to consider a window with shutters. The shutters are the aperture, the length of time the shutters are left open is the shutter speed.
And the ISO will be yourself standing inside the room with a pair of sunglasses on. There are three ways in which light can enter the room. The first is to open the shutters.
The second is to keep these shutters open for a longer period of time. The third is to remove the sunglasses.
Note that with the exposure triangle, the more light that is allowed to enter, the more overexposed your shot will be, because more light will be allowed to enter. But this is where your own creativity comes into play, because these controls are what will form the basis of all your photography.
For example, if you are shooting a high action shot, for example, cars racing. To get a good crisp shot of a car racing by, you will need to have a very fast shutter speed.
This will mean that the shutter will be open for a very short amount of time, meaning little light will enter your camera. To compensate for this, your exposure triangle will come into play.
You can combat this by either increasing the ISO to make your sensor more sensitive to the small amount of light it does see, or you can make your aperture wider to allow more light into the camera.
Increasing either or both of these settings will give you a sharp crisp shot correctly exposed.
In another example of how the exposure triangle works, you may wish to photograph a scenic landscape. For this to work best, you will need a very small aperture because there will be a great deal of light and you do not wish to over expose the image.
Furthermore, with aperture, something called depth of field comes into play where large apertures mean that only a certain portion of the shot will actually appear to be in focus.
A small aperture size means that everything will appear to be in focus. The downside to this is that you will again need to understand the exposure triangle and realize that the shutter will probably need to be open a little longer in order to receive enough light for the image.
A tripod may be of use here, as holding the camera steady for more than 1/60th of a second is nigh impossible.
This forms a general explanation of how the exposure triangle of aperture, shutter speed and ISO all relate to one another. More detailed explanations of each element can be found in subsequent articles.
But in essence, mastery of the exposure triangle is vital for any amateur or serious photographer to take their photography to the next level.
Now head on over to Part 2: Understanding the Role of Camera Aperture