How important is exposure in photography? What are the components of exposure? What is Exposure Triangle? These are the questions I will attempt to answer as I go along and talk about ISO, Aperture and Shutter Speed; factors essential to achieving good exposure. Understanding the purpose and value of exposure is a must for photographers, including beginners, who are serious about developing their craft.
What is Exposure in Photography?
In the simplest of terms, exposure for photographers refers to how an image is recorded by camera sensor. How light or how dark is it? Is it underexposed or overexposed? Basically, it helps determine how the image you shot will look like.
To achieve the right exposure, you need to consider three things: ISO, Aperture settings and the Shutter Speed.
Understanding the Exposure Triangle
The ISO, Aperture and Shutter are known as the “exposure triangle”. If you know how to control or adjust these elements, taking well exposed photos will not be a problem for you.
Let us look at each element closely and understand how they can help you achieve the right exposure.
The Exposure Triangle is the visual representation of the relationship between three main components of the Exposure: ISO, Shutter Speed, and Aperture.
The ISO refers to ratings that define the sensitivity level of your camera to light. ISO value is determined by numbers: the lower the number, the lower its sensitivity to light. Higher values mean it is more sensitive to light. Depending on your camera, the lowest value is 50, 100 or 200.
Photographers need to know and understand proper ISO settings. For example, if you want more saturation and less noise and more details, go for ISO 100. If you want less saturation and details, go for a higher number, like an ISO of 400. Each time you increase the ISO to a level, the sensor’s sensitivity is doubled (ISO 100 to ISO 200, ISO 200 to ISO 400, and so on). This means that you are actually allowing twice the amount of light into the sensor. Thus, exposure is increased by a factor of 2.
In the same manner, if you want to take a photo of the early evening skyline, you will need to consider that it is already dark, so you will need a high shutter speed to properly capture the image. What you can do is increase the level of sensitivity to 3200 so that exposure is increased by five (100-200-400-800-1600-3200).
Once you learn how to take advantage of the ISO, you can experiment with the images you want to capture. You can create different ways of presenting your subject. In addition, you will also be more comfortable shooting in different lighting conditions.
If the ISO is related to light sensitivity, the aperture is all about controlling the amount of light that goes through the digital sensor of your camera. It is found in your camera lens. If you look closely at the camera lens, you will find round or ring-like metal blades. These blades open and close: it opens to widen the opening; it closes if you want the opening to narrow down.
As such, controlling the aperture or choosing to use the Aperture Priority mode allows you to adjust the amount of light that can get into your camera so that it can either open (widen) or close (narrow). The aperture setting is determined by several f-stop values. The usual numerical values for the f-stop are 1.4, 1.8, 2.0., 2.8, 3.6, 4, 5.6, 8, 11, 16 and 22.
When you adjust the aperture, note that as the numerical value increases, the aperture becomes smaller and the amount of light that gets through decreases.
So, if you need to remember one thing, it is this: when you adjust the aperture by just one stop, you either halve or double the amount of light that goes through your camera lens. Or, you can also refer to an f-stop chart. What is important, though, is that you keep practicing until you familiarize yourself with the different f-stop values, and until you produce the image/s you want.
The shutter of your camera is the one you hear clicking or snapping. Whether you use a DSLR or a point-and-shoot, or even just your smartphone, you are sensitive to this sound. This is the sound that tells you that a photo has been shot.
For photographers, though, what is more important is the shutter speed. Every time you press the shutter button, a door that opens and closes is found in front of your camera’s sensor. This is the shutter mechanism that determines the length of time the sensor is exposed to light. In other words, it controls the amount of light that can get to the sensor.
The shutter speed is measured in fractions of a second, e.g. 1/100s. So, if you use the example given, 1/100s, what this means is that your camera sensor is exposed to light for only one hundredth of a second. If you need to remember one thing about shutter speed, it is that when the shutter speed number is higher, the faster the shutter opens and closes.
If you want to control the shutter speed manually, go for Shutter Priority (S or Tv on your camera) or manual mode.
When you are confident in using the shutter speed, you can play around with your photos and make them come out more creatively. Of course, practice makes perfect. So, don’t forget to do just that.
Combining the ISO, aperture and shutter speed results to an equivalent exposure value for a particular setting. If any one of these elements is adjusted, the resulting image will not be the same. If you increase the f-stop to decrease the amount of light getting to the sensor, you will also need to adjust the shutter speed and the ISO; otherwise, your image might come out blurry or too bright; overexposed or underexposed.
This is just a simple introduction to the three elements that make up the exposure triangle. If you want a more detailed discussion about ISO, shutter speed and aperture, you can find them in the following articles:
- Learning Shutter Speed With Shutter Speed Chart
- Learning Aperture in Photography With F-Stop Chart
- What is ISO in Photography?
Or, if you want quick answers, you can always leave a comment.