Understanding Shutter Speed

Shutter Speed

There is a mechanical component in cameras called the shutter. It's like a little window that opens and closes when you press the shutter button on your camera. It's function, is to allow a certain amount of light into the camera based on time. 

Shutter settings are represented in time. For example, you could have a 15" (15 second) shutter speed or a 1/160 (160th of 1 second) shutter speed. 

Shutter speed will have two main functions to your photographs.

  1. Change the amount of light coming into the camera, based in time.
  2.  Add motion blur, or freeze moving objects in place

A slow shutter speed and a fast shutter speed depends on your subject.  If your subject is a really fast moving bird, you're going to want to shoot at a high shutter speed. The reason being is that you will likely want to capture the bird in flight, which is a very fast motion. A fast shutter speed will freeze the birds motions in place, and not create and blurriness. 

 

Ever get those shaky looking photos? That's from a slow shutter speed. Sometimes a slow shutter speed is desired, and other times it is a necessity. 

For example, you may wish to use a slow shutter speed to intentionally show motion in your subject. If you're like me, then maybe you want to show motion in water by shooting at a slower shutter speed.

 

No Photshop required! This effect is achieved in camera by slowing the shutter speed down

No Photshop required! This effect is achieved in camera by slowing the shutter speed down

In other cases, you may be required to use a slow shutter speed by seconds. This is called a long exposure and is used when you are photographing of the stars. If you are going to be shooting at a slow shutter speed, you absolutely must have your camera on a tripod, and preferably shooting with a wireless trigger. This is because any slight movement in the camera, even your finger gently pushing on the shutter button, can cause a slight movement which will be evident in the final photograph. 

TL;DR

  • Shutter speed controls the amount of light coming into the camera, based in time
  • A slow shutter speed will allow more light to come into the camera
  • A fast shutter speed will allow less light to come into the camera
  • Shutter speed is represented in fractions of a second - 1/160 = 160th of 1 second
  • Want to freeze a splash of water so that you can clearly see every single droplet? Use a fast shutter speed.
  • Want to shoot the stars, or write your name with a sparkler? Use a slow shutter speed

Understanding Aperture

A big part of understanding how to user your DSLR properly is understanding the aperture. The aperture is an opening in the lens, which allows for a certain amount of light to reach the camera's sensor.

The aperture in a lens is typically controlled by the camera. You can make the aperture larger or smaller which has two main effects. 

  1.  Allows more or light to reach the camera's sensor.
  2. Changes the depth of field
aperture .gif

 

The aperture in a lens works the same way our pupils do. If you shine a bright light into your eye, your pupils constrict. This is to prevent too much light entering into your eye, which would be blinding.  If you sit in the dark for a while, your eyes will dilate. This is to allow more light to enter your eye, so that you can see better in the dark. The aperture works in a similar fashion. 

You can make the aperture smaller, which will allow less light to reach the camera's sensor. This also will make the depth of field larger. An example of a small aperture is f/22.

You can make the aperture larger, which allows more light to reach the camera's sensor. This will also make the depth of field narrower. An example of a small aperture is f/2.8. 

Shallow depth of field vs. Deep depth of field

Shallow depth of field vs. Deep depth of field

 

Aperture works in conjunction with the camera's shutter speed and ISO setting to properly expose an image. However, often times it's best to start with setting your aperture setting first, and then changing the shutter speed and ISO settings afterwards. 

When should I use a shallow depth of field or deep depth of field?

Ultimately, you have creative control to answer that question. However, typically a shallow depth of field is used for shooting a portrait of a person and a deep depth of field is used to photograph a landscape. Use a shallow depth of field when you really want to have a single subject be in focus. Use a deep depth of field when you have multiple subjects you want to be in focus, or you are photographing a large area like a landscape.