Photography and the Exposure Triangle

The exposure triangle may seem like a weird “theory” that isn’t necessary to learn, but if you want to call yourself a photographer and take control over your equipment this should be second nature to you. The exposure triangle is the fundamentals of photography. Just like the name implies, it is a triangle with: Aperture (F/stops), ISO and shutter speed. You can take the same exact picture with different setting inputs and come out with completely different images. Aperture, Iso and shutter speed work together to gather the amount of light needed for a correctly exposed photograph. If one variable changes, at least one of the others must also change to maintain the “correct exposure”.

Shutter Speed.

Shutter speed refers to the length of time the light is allowed to hit the sensor, which is measured in seconds.Each element in the exposure triangle target a specific area. When talking about shutter speed, it involves movement. Do you want motion blur or do you want to essentially freeze time? You would manipulate your shutter speed to help you achieve any of those looks. Now when it comes to shooting in Manual mode, you cannot just focus on one element. I am simply isolating the three to give in depth knowledge.


Put simply, Aperture is the opening in the lens. When you hit the shutter release button of your camera a hole opens up that allows your cameras image sensor to catch a glimpse of the scene you’re wanting to capture. The aperture that you set impacts the size of that hole. The larger the hole the more light that gets in – the smaller the hole the less light. Since I said earlier that shutter speed went hand and hand with motion, Aperture refers to Depth of Field (DOF). Aperture is what usually confuses beginners due to the fact that it seems backwards. A f/stop of 2.8 is much larger than a f/22.


In very basic terms, ISO is the level of sensitivity of your camera to available light. The lower the ISO number, the less sensitive it is to the light, while a higher ISO number increases the sensitivity of your camera.The component within your camera that can change sensitivity is called “image sensor”.With increased sensitivity, your camera sensor can capture images in low-light environments without having to use a flash. But higher sensitivity comes at an expense – it adds grain or “noise” to the pictures. Here’s a simple chart to help you understand (don’t you just love charts)

You might be asking, what is noise? I know when I first started in photography, hearing people say “noise” was confusing. How can you have a noise in a still photo.Well noise is very important because it can come out in your photo and ruin it if it wasn’t wanted.

There you go. The right side of this image has those little grainy dots all over which is what photographers call “Noise. Granted, you might want to have that in a photo, but most of the time we want crisp photos that are clean.

Now put it all together.

Creating a perfect exposure using the aperture, shutter speed and ISO is a juggling act. As soon as you make a decision about one element, you’ll need to compromise with another.Don’t panic, it can take a while to understand how one effects the other but if you really keep studying the three elements you will find your own balance that you like the most.


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