Back to Basics #2 – Shutter Speed

Shutter Speed Facts

If the aperture controls the amount of light that falls on the camera sensor/film, the shutter determines how long that light falls on the film/sensor. Choosing the correct shutter speed is important because:-
* It can freeze a moving subject.
* It can blur moving subjects.
* It can help reduce camera shake.
So, how can we use the shutter speed to best advantage?

The ‘safe speed’ to hand-hold a camera used to be around 1/60th if a second. Any slower and the image could be blurred by camera shake. Nowadays with image stabilisation it’s possible to go to even lower shutter speeds, and mirrorless cameras can go to speeds as low as 1/8th sec quite successfully.

Camera shake.
Generally though if you intend to shoot at 1/30th or less it’s wise to use some form form of support.

Moving objects.
The shutter speed determines the amount of time that the film is exposed to the reflected light off the subject. If the subject is moving then the longer the exposure the more movement will be recorded on the sensor/film. Think about what you want as an outcome. Do you want the moving object to be deliberately blurred to give the impression of movement or do you want it to be frozen – so that it’s captured with all its detail sharp? To freeze it in time choose a fast shutter speed, 1/500th sec for example. To blur it choose a slow shutter speed – say around 1/60th sec.
Don’t forget too that you can use a slow shutter speed and ‘pan’ the camera – follow the moving object with the camera, giving the effect of a blurred background and in focus subject. This technique is great for moving vehicles and bicycles. This takes some practice – but it produces striking results. (One of the best examples I have seen was an image of a motorcycle captured from a car sitting parallel with it on a dual carriageway – where the camera pan was achieved by the motion of the car).

Shutter Speed and Flash.
Generally cameras will have a flash sync speed. On modern cameras it’s usually around 1/250th sec. (Some new cameras can use high speed sync with dedicated flash guns – but using flash set to automatic or to TTL is not the best way to use your flashgun). On many cameras the sync speed will be indicated in red letters or with an X.
If you exceed the sync speed the flash will fire before the shutter has had time to fully open, and part of the image will not be exposed. On your digital camera this will show on the LCD as a black section along one side of the image.

Flash Sync
Long Exposure.
On some cameras there are two settings marked ‘B’ and ‘T’. These stand for

  • Bulb. To use this setting press the shutter button and hold it until the exposure is complete and then release the shutter button.
  • Time. In this setting press the shutter button and release it. The shutter will open. Time your exposure, the press the shutter button again to bring the exposure to and end.

Both these settings are used when long exposures are needed, in nighttime photography for example, to achieve sharpness of focus with a tiny aperture.
Another application of this technique is to freeze water – for example a waterfall or river or even the sea.
Needless to say both these settings really need a tripod and a shutter release cable or wireless shutter release to be successful.

Shutter Priority.
This mode allows the photographer to select the preferred shutter speed (say to freeze motion in a sports match) and allows the camera to automatically select the aperture. The photographer should select the ISO with intended outcome in mind. If a low ISO is selected, and a shutter speed of say 1/250th sec the aperture will probably be wide open and the depth of field greatly reduced.