Exposure Triangle Explained

Shutter Speed | Aperture | ISO

If you are just branching out into SLR photography, you may be starting to pluck up the courage to play about with the non-auto settings and try out some of the camera’s manual capabilities. But before you do that, let us understand the Exposure Triangle.

One of the cornerstones of basic photography is learning about and understanding the Exposure Triangle.

The Exposure Triangle is the name given to the three main elements of the camera’s exposure: the ISO, the Aperture, and the Shutter Speed.

Exposure Triangle
Exposure Triangle: Shutter Speed, Aperture & ISO

These elements all help to control the amount of light which is getting to the digital light sensor in the camera.

  • The ISO is the name given to the basic measure of light sensitivity in your digital camera. Read more about ISO.
  • The Aperture is the size of the opening in the lens. This opening controls how much light is let through to the digital sensor in the camera. Read more about aperture & shutter priority modes.
  • The Shutter Speed is the length of time that the shutter of the camera remains open for when a picture is being taken.
Basic Photography: Exposure Triangle
Graphic Credit: Boogies with Fish

Many teachers of basic photography like to use the Window Metaphor to describe the exposure triangle. In this metaphor, you must imagine a room with a window. On the outside of the window are plastic shutters and on the inside is a thin, semi-transparent curtain.

The aperture is the size of the window – a big window means lots of light can get into the room. A tiny window would mean that the room was dimly lit. When the shutters are open, light can get into the room, but when the shutters are closed, the room is dark (Shutter speed > how long are is the shutter open).

Related Post: Getting out of Auto Mode

The amount of light that can get into the room also depends on the thickness of the semi-transparent curtain (ISO). A thick curtain will prevent much light from getting in and a thin curtain will allow nearly all of the light to get in.

Once you understand the differences between these elements, you will be able to start using them to take control over your pictures. Long shutter speeds and large apertures are great for taking night shots, where there is a not as much light, however, if you crank up the ISO as well, you may end up with grainy shots.

Exposure Triangle Explained
Exposure Triangle: How Different Exposure Settings Affect Your Photos | Image Credit: Bangdoll

Fast shutter speeds are great for capturing motion. Subtly playing with each of these settings is the best way to get a feel for them. Don’t begin to alter other things on the camera until you know how to use these features properly. 

Let’s do some Basic Photography Workout!

Aperture Mode Priority

Aperture Values
Example for Aperture Values (F2 – F22)

Shoot some photographs with a low aperture value (=big aperture size, more light, “bigger window”).

Examples @ F 1.4 or F 2.8: This mode is ideal for portraits, indoors and night scenes.

d700 at 50mm f/1.4
D700 at 50mm f/1.4
Low aperture value
photo credit: Atheist_Lenses

Shoot some photographs with High Aperture Value (Less light, smaller “window”), which is deal for landscape photography and wide depth of field (more sharpness), e.g. f/22.

High Aperture Value
photo credit: Frank Kehren
High Aperture Value
photo credit: lord_yomismo

Shutter Speed Priority

Freeze the Moments vs. Show Movement

To capture a movement in a sharp way, use a low shutter speed

High Shutter Speed

Low Shutter Speed
photo credit: sparktography
Sports Photography
photo credit: pedrosimoes7

Slow / Long Shutter Speed

Slow Shutter Speed
photo credit: Troels Dejgaard Hansen
Long Shutter Speed
photo credit: Werner Kunz

Basic Photography Tip: If you are taking photos in the aperture mode the shutter speed will automatically adjust to let more / less light in. And if you are shooting in the shutter speed mode the aperture will adjust. Suppose you keep the ISO unchanged, the shutter speed/aperture combination will always remain the same.

Shutter Speed and Aperture combination
The aperture/shutter speed combination will always remain same. You just set the priority!

Featured Image Photo Credit: Tomi Tapio K


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