A continuous light such as a torch or candle can be mixed with flash light to create a composite negative with two exposures.
How to get this effect:
1. Set the camera to multiple exposure.
2. Use the camera on a tripod with a cable release.
3. Meter for the flash light (or overhead/daylight in the case of the Picasso or Dance Hall images) and make the 1st exposure.
4. Then in a darkened space where the torch is the only light source use a long exposure to record the movement of the torch (this could be about 20 seconds for example).
5. The torch light will register much better on a dark background than a white one.
Light from any source – a window, a continuously burning lamp, a flash – foltows the same general rule: The light falls off (gets dimmer) the farther the light source is from an object. But light from a flash comes and goes so fast that you can’t see the effect of the flash on a scene at the time you are taking the picture. Special exposure meters are designed for use with flash; you can’t use an ordinary exposure meter to meas.
The following table shows the correlated colour temperature of common light sources:
Color Temperature
Light Source
1000-2000 K
Candlelight
2500-3500 K
Tungsten Bulb (household variety)
3000-4000 K
Sunrise/Sunset (clear sky)
4000-5000 K
Fluorescent Lamps
5000-5500 K
Electronic Flash
5000-6500 K
Daylight with Clear Sky (sun overhead)
6500-8000 K
Moderately Overcast Sky
9000-10000 K
Shade or Heavily Overcast Sky
Here is a visual representation of the Kelvin temperature scale. Notice how lower temperatures are very warm, and following the color spectrum, increase in numeric value as they become cooler.
The most realistic and usually most pleasing lighting resembles daylight, the light we see most often: one main source of light from above creating a single set of shadows. Lighting seems unrealistic (though there may be times when you will want that) if it comes from below or if it comes from two or more equally strong sources that produce shadows going in different directions.
Flash can be used in conjunction with ambient (already existing) light. It can be very useful as a secondary light source to fill in the shadows of natural light, without losing the basic light & shade patterns nor the general atmosphere.