Want to make the best use of your advanced digital camera? Well, one way is to move out of using its automatic mode settings, and try out some of its manual settings. As the title suggests, we are going to learn about the photography exposure triangle in this post. But before that, let’s understand what exposure actually is. Camera exposure is simply the amount of light that enters your camera sensor when you are clicking a photograph.
And why should you care about the amount of light that enters the camera sensor? Simply put, more light typically means a narrower field depth, which focuses the camera on the subject. On the other hand, lesser light means a larger field depth, which is ideal for capturing landscape images.
Now that we have that out of the way, let’s delve into the elements that make up exposure triangle photography.
What are the Elements of Photography Exposure Triangle?
The photography exposure triangle is simply the combination of 3 elements or variables, namely, aperture, shutter speed, and ISO. Balancing these 3 elements is the key to high-quality photography.
So, what is the exposure triangle? Let’s look at each of these elements in detail.
The aperture is what determines the size of the opening in your lens, when it focuses on a subject. It is measured in units of “F/stops.”
Look at the relative sizes of the lens opening for different aperture sizes.
As you will notice, larger apertures have lower f/stops (example, f/1.4), which basically means that a greater amount of light enters your camera. On the other hand, smaller apertures have greater f/stops (example, f/8) which means that lesser amount of light enters your camera. Most camera lenses capture the sharpest images at aperture sizes of f/5.6 or f/8.
As a rule, the light-collection area quadruples each time the f/stops are halved.
What is the Depth of Field and how is it impacted by the Aperture?
The depth of field basically determines the focus of your camera shot. A larger depth of field is used for a wider shot. For example, in the case of the following landscape shot, where the boats in the foreground and the mountain in the background are both in focus.
A smaller depth of field is used to focus on a particular image, where the rest appears fuzzy or blurred.
For more information on how to use Aperture, read What is Aperture in Photography – Know the Basics.
Now that we have discussed aperture, let’s move on the next element of photography exposure triangle.
The shutter speed determines the time for which the camera sensor is exposed to the incoming light. In modern cameras, shutter speeds can range from extremely fast (1/4000 of a second) to 30+ seconds for low light or night photography.
A faster shutter speed provides lesser time for your camera sensor to collect light, hence resulting in low exposure. Slower shutter speeds, on the other hand, provide more time for your camera sensor to capture light, resulting in higher exposure. Shutter speed impacts the sharpness of the captured image, with lower shutter speeds leading to blurred images.
Here are some typical examples of when to use different shutter speeds:
Shown below is an example of a long shutter speed of 6 seconds.
Below is an example of fast action snapshot at a shutter speed of 1/4000th of a second.
Changing your shutter speed also has an impact on the aperture size. For example, changing the shutter speed from 1/125 to 1/250 of a second will require that you change the aperture from f/16 to f/11. Most of the time, you will probably use a shutter speed of 1/60 or higher. For shutter speeds slower than 1/60, you must use a tripod to avoid camera shakes.
The ISO speed is typically used to adjust the camera sensor to detect the amount of light (more or less) to get a good exposure. Lower ISO speeds result in a lower sensitivity of the image sensor to the incoming light, resulting in finer photography.
Unlike the other 2 elements, a lower ISO speed is preferred, as higher levels of ISO speeds can increase the image noise. As a rule, you should use the ISO speed at its minimum value (typically, 100).
Why increase ISO at all then? As a recommendation, you should use higher ISO speeds only in darker scenarios, where you would want to capture the image with faster shutter speeds (for example, an indoor sporting event). You can also use a higher ISO for other events such as low-light concerts, art galleries, or to capture the blowing of candles during a birthday party to get a nice shot without the use of camera flash.
Modern cameras have ISO speeds ranging from 100 (ideal for a bright sunny day) to over 25,000 (night photography).
For using ISO, read Understand ISO in Photography in 4 Simple Steps.
You can see the difference in the following shots taken at different ISO speeds. While the left image has been captured at 100 ISO, the right image was captured at an ISO of 3200.
Combining the 3 Elements
As we have understood, photography exposure triangle is a balance of its 3 elements, aperture, shutter speed, and ISO. The specific combination of these three elements is termed Exposure Value (EV). An exposure is measured in terms of “stops,” with each adjacent stop representing either double or half the level of exposure of the next stop.
In simple terms, reduce the stop by 1 to reduce the exposure level by half, or increase the stop by 1 to double the exposure level.
You can control the exposure by using shutter speed. For example, a shutter speed of 1/50 seconds is 1 stop lesser than a shutter speed of 1/100 seconds. Similarly, an ISO of 400 is 1 stop more than an ISO of 200, while being 1 stop less than an ISO of 800. When it comes to aperture size, an aperture of f/5.6 would be 1 stop smaller than f/4.0, but 1 stops greater than an aperture of f/8.0.
Let’s see how you can achieve a balance between the 3 elements. As a general practice, if you increase any of the 3 settings, then you must decrease any one or both remaining elements to maintain the same exposure level. For example, for an ISO of 100, an exposure with a shutter speed of 1/25 seconds and aperture f/16 would be equivalent to an exposure with a shutter speed of 1/400 seconds and aperture f/2.8.
In this case, the shutter speed has been increased by 4 stops (1/25, 1/50, 1/100, 1/200, and 1/400), hence the aperture size had to be decreased by 4 stops (f/16, f/11, f/8, f/5.6, and f/2.8).
As a photographer, you can master the art of the photography exposure triangle through a lot of practice and by trying out different settings of aperture, shutter speeds, and ISO. You will eventually find the right balance of all 3 elements, depending on the photographic settings and light conditions.