Photography Basics: Shutter Speed

waterwheel toy shot with fast and slow shutter speed

This article looks at how to:

  • either avoid, or purposefully include, blur due to camera shake or movement of the subject, camera or lens
  • freeze motion.

Slow Shutter Speeds

For this exercise I used shutter priority mode (something I don’t normally do) which means that I set the shutter speed and chose the ISO, and the camera chose the aperture needed to properly expose the photograph.

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Photography Basics: Aperture

Whenever a photograph is taken, a decision has to be made about how much light is needed to achieve an acceptable exposure. Often the camera will automatically select a shutter speed, aperture and ISO to control this. However, the photographer may decide to select one or more of these variables themselves.

The aperture of a lens refers to the size of the opening through which light passes. A certain lens will have a maximum aperture (the size when it is as wide open as possible) but can be set to close down to a narrower size.

If two photographs are taken under the same conditions,  using the same shutter speed and ISO but with different apertures, then the photograph with the smaller aperture will appear darker. A small aperture lets in less light than a large aperture.

The progression of apertures (in “stops”) is as follows: f1.4, f2, f2.8, f4, f5.6, f8, f11, f16, f22, f32… Closing down the aperture by one stop halves the amount of light reaching the sensor, so the shutter has to stay open for twice as long to let in the same amount of light.

(diagram from Wikimedia Commons)

The photographs below demonstrate the effects of changing the aperture. Not all lenses can achieve every possible f stop. For the experiments shown below, I used a lens whose widest aperture was f2.8.

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