Shoot outdoors at night against a dark background. Open the camera shutter while someone forms letters in the air with the light. Experiment with different lens apertures so that the light source is not overexposed. One variation is to fire the flash at the start of the exposure so that the person writing the words is visible. The length of the exposure needs to be sufficient for the word or words to be formed.
Silverter Heiß, © Alfred Utrata 2009, Canon PowerShot A70
One special long exposure technique acts like magic to clear a scene of moving people. You need a high-density neutral density filter. This attaches to the screw mount at the front of your lens. The filter greatly reduces the amount of light passing through to the lens. This means that you must increase the exposure time for enough light to reach the digital sensor.
Canon offers two versions, the ND4X-L and ND8X-L, which cut the amount of light reaching the sensor by a factor of 4 and 8 respectively. With an exposure time of, say, two minutes in daylight, any moving person in the shot will disappear – they will not be in one place long enough for an image to form.
If you do not have a tripod, you can still experiment with long exposures. Photograph illuminations at night while deliberately moving the camera up and down or side to side. An exposure time of just a few seconds will give a heavily blurred image that is almost abstract in nature. It is not an effect everyone will appreciate, but can be fun to shoot. Review the images on the camera’s LCD screen and adjust the exposure time, lens aperture and movement to improve the results.