An earlier posting, Slices of time, looks at the effect of freezing subject movement with a fast shutter. My conclusion is that the sense of movement is lost, even if the subject is in a statically unsustainable position such as mid-air.
This post looks at some examples of blur due to subject movement and a slow shutter.
The first category results from shutter speeds that are hand-holdable but too slow to freeze a fast moving subject. This includes one of my favourite images, by Sergio Larrain during his time in London in 1958-59. The girl and her surroundings in Trafalgar Square are still, but the pigeons have been recently disturbed and their blurred wings give a sense of movement,flurry and confusion.
Blur of this type can be seen in some sports and concert reportage as a result of high subject speed or low light respectively. It can also be used as a stylistic preference, for instance by Robert Frank in ‘Elevator – Miami Beach 1955’ . The lift (‘elevator’) attendant appears sharp as part of the fixed scenery while the hotel guests have somewhere to go, and are moving and blurred as a result. Taken with her bored expression and eyes directed upward, we feel something about the drudgery of her job.
Longer shutter times require the use of a tripod to hold the camera steady. Fixed objects are rendered sharply while moving objects are blurred. The technique is used with water and clouds often enough to have become a cliche. Cloud example by Michael Kenna. When the moving elements have an one-way movement, as with clouds, waterfalls or rivers there is a feeling of flow. Where the movement is cyclic, such as waves on water, then long exposures tend to even it out and the sense of motion is lost. Example here.
Long exposures can reveal movement that is not obvious to the naked eye, for instance star trails.
The course notes refer to the images of Hiroshi Sugimoto, who photographs inside cinemas, opening the shutter at the beginning of the film and closing it at the end. Frankly, these images leave me cold. The screen appears as a blank white rectangle, which is the effective light source for a view of the cinema interior. There is no sense of motion or of time passing. Example here.
Michael Wesely uses even longer exposures, measured in weeks or months, which can capture the whole progress of a building project. Examples on this page. This gives a good impression of time passing, but not of motion – his subjects are essentially static, although growing. The bands of light in the sky represent the track of the sun, varying from day to day in the same way as a Justin Quinnell solargraph.