The Exposure Triangle: Understanding The Basics

What is The Exposure Triangle?

Before now, we discussed the three primary factors that determine the exposure of a photograph; which are the Aperture, Shutter Speed and ISO. (These factors as stated here have clickable links that would take us to the previous posts where we discussed them in detail just in case we need to refresh our memory).

Now Exposure Triangle is the act of striking a balance between these three variables so as to produce a perfectly exposed image.

APERTURE

The Aperture can be defined as the diameter of the channel through which light passes to get into the image sensor. The Aperture is measured in f-stops. So an Aperture value of f/1.8 has a wide opening while an Aperture value of f/22 has a small opening.

With Aperture comes Depth of Field. The depth of Field here refers to how much of your image is in focus. So shooting with a wider aperture makes less of the image be in sharp focus while shooting with a smaller aperture makes more of the image be in sharp focus.

SHUTTER SPEED

Shutter speed refers to the length of time the shutter is open. So if you’re shooting with a fast shutter speed, for example, 1/1000th of a second, less light gets into the image sensor compared to when you’re shooting with a slow shutter speed of 1/10th of a second which allows more light into the image sensor.

When shooting with a wide aperture, your shutter speed will need to be fast to compensate for the amount of light entering the camera otherwise you’ll most likely end up with an over-exposed image. Same applies if you’re shooting with a small aperture, your shutter speed will need to move slower to enable more light into the camera otherwise you’ll most likely end up with a grossly under-exposed image.

Your shutter speed can also be used to freeze motion. So if you’re taking a photograph of a moving car or a waterfall, using a fast shutter speed freezes the movement. A slower shutter speed will produce a blurry image of the car and a creamy look of the waterfall. These outcomes are not necessarily bad if done creatively.

ISO

This refers to the way your camera interprets light; This is also known as the Image sensor’s sensitivity to light. This sensitivity is measured in figures like 100,200,400,800 etc.

So a camera with a base ISO of 100 means that the best picture quality is to be taken at this setting and this requires enough light and excellent conditions for it to perform. A camera with an ISO setting of 4000 would require less light to take a bright image but this could be at the expense of the quality of the image as there could be the existence of image noise or grainy pixels in the picture.

If you’re taking a photograph in a dimly lit room, you can introduce an external light source like a Speedlite and still operate at a low ISO to ensure the digital noise is kept at it’s barest minimum.

CONCLUSION

In summary, this is an idea of what the exposure triangle is all about. Effective utilization of these three variables; Aperture, Shutter Speed and ISO to produce a perfectly exposed image. So it’s time to pick up our cameras and get practising. You could share your images in the comments section below or on our community lets all learn.

If you have any questions or contributions to make, kindly share your thoughts in the comments section below.

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APERTURE : Understanding Exposure in Digital Photography

On our series of demystifying photography, we’ll be looking at one of the three cardinal factors that determine exposure in photography; which is Aperture. The other two are ISO and Shutter speed. Before we go ahead, it’s advisable we have a good knowledge of the structure of a DSLR camera

What Is Aperture

Aperture can be defined as an opening in a lens through which information in form of light travels into the camera body/structure. This could vary in size. The larger it is, the more light that gets into the camera.

Aperture Size

The size of the aperture can be controlled by the Iris. In Digital Photography, the aperture is measured in f-numbers (for example f/8). The f-numbers or f-stops can be used to describe how wide or narrow the aperture is. A smaller f-stop means a larger aperture while a larger f-stop translates to a smaller aperture. This is another area photographers find confusing but once you understand the ideology, it sticks.

Below a graphic representation of Aperture.

Aperture Explained
Aperture Explained

Depth Of Field.

We can hardly discuss Aperture without making reference to Depth of Field. Depth of Field can be defined as the amount of your shot that is in focus. A large Depth of Field means that most of your image would be in focus. This can be produced using a small aperture (large f-number/f-stop) such as f/16.

Large Depth of Field
Large Depth of Field (Large F-number/Small Aperture) F-stop f/13 Exposure time 1/160secs ISO 160

A small or shallow Depth of Field can be seen as an image with only a portion of it in focus while the rest of it remains blurry or fuzzy.

Shallow Depth Of Field
Shallow Depth of Field (Small F-number/Large Aperture) The image was taken at the LetstalkphotographyPH meeting f-stop f/1.8 Exposure Time 1/200 secs, ISO 1600 Focal Length 50mm Subject Distance 2.5m Metering Mode Centre Weighted Average No Flash

DSLR Lenses are manufactured to have specific values on how wide or narrow the aperture can get. The lens specifications usually state the largest f-stop and the smallest f-stop. A lens with a maximum f-stop of f/1.2 is considered to be a fast lens because it allows more light to pass through compared to a lens with a maximum aperture of f/4.0

Here's a brief video produced by Olufemii Tutorials that also explains Aperture

We tried to keep things as simple as possible while explaining Aperture as it relates to Exposure in Digital Photography. Feel free to share your thoughts in the comments section below.

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