Recording motion with a fixed camera (0.3a)

Requirement

10 - 12 photographs

Purpose

To show how to adjust shutter speed to capture motion, either to freeze action or to give varying levels of motion blur

Technical learning

• A fast moving object needs a fast shutter speed to render it sharply
• If not, part or all of the subject will be blurred
• Nevertheless, motion blur in an image can be very effective in giving an impression of speed

Exercise instructions

Use a tripod. Set camera to shutter priority. Pick an object that moves across your view several times or continuously, e.g. water following across rocks, cyclist, cars. Shoot against a plain, simple background. Take a series of exposures from fastest shutter speed of your lens to a slow speed (e.g. 1/2 sec). Note the shutter speed of each image.

Images and review

Location: Road under Blackfriars Railway Bridge, London

Time: 7.30am, a Friday in early August

Aim: Capture the movement of cyclists passing under the bridge, most of whom presumably are on their way to work

What are you looking at?

1/400 - subject is crisply sharp, looks towards the camera

Just another work day

1/125 - cyclist is slightly past sharpAdd caption

Cyclist and pedestrian converge

1/100 - faster moving of 2 subjects is now blurred, whilst the other is still sharp

2 cyclists overtake a stroller

1/80 - Cyclists become more unsharp, walker is still in focus

Van and bike close on a glum looking walker

1/60 - Car and cyclist are significantly blurred, pedestrian is still sharp

A ghost on, rather than in, the machine

1/30 - cyclist is heavily blurred

Even walkers are started to melt down

1/15 - cyclist almost unrecognisable, pedestrians are becoming blurred

Cycling in the abstract

1/10 - cyclist detail breaks down further

Is that someone in the fog?

1 sec - walker just about visible within the streak created by a passing white van

The Roadrunner overtakes the bus ... meep, meep!

1.6 secs - only a bus at its stop remains identifiable

Total abstract

2 secs - anything that moves just leaves a formless trail

Further learning

• 2 main factors affect the crispness of a moving object. These are: (a) its speed across (or towards) the frame and (b) its distance from the camera. The greater speed, or the closer the subject is to the camera, the faster the shutter speed required to freeze motion, or achieve a desired amount of motion blur
• The sharply rendered moving subject often gives a weak impression of movement. This can be partially offset by the presence of other clues of speed. Such clues include: placement of significant space in front of subject (prompting the perception of motion into the available space), capturing the frozen step in an evidently vigorous movement (e.g. a mid air leap by a dancer), using a setting strongly connected with movement (e.g. athletes competing in a race)
• Use of a plain background helps to focus attention on the subject and therefore on its motion, whereas a busy backdrop distracts attention from the subject and consequently weakens the impression of its motion