Lightning unleashed

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A passive (battery-free) servo flash trigger with suction cup on a handheld flash unit

With unbridled flash in which you referred Photography use a flash unit, the space of the camera is disconnected.

The flash unit is controlled either via a connection cable or wirelessly. The wireless transmission takes place via infrared , radio or a triggering by the flash of another flash. With exposure times of several seconds or more, the flash unit can also be triggered manually.



Common names for the device or flash used to control the other flashes are: master, transmitter or main flash.

Common names for the unleashed, remote-controlled flashes are: servo flash, slave flash, daughter flash, slave or slave flash

Working principle

Modern system cameras can operate several flash units together and integrate them into the automatic exposure measurement.

Due to the pre-flashes that are common with digital cameras and their built-in flash units (e.g. to measure the distance to the subject and the exposure), conventional servo flash units and triggers cannot be used here. Rather, those with special circuits are required that ignore pre-flashes and only ignite during the actual main flash. The additional pre-flash against red eyes must also remain switched off.


In the beginning it was only possible to optically trigger further flashes via a photo cell, but soon triggering via radio signals was possible, which had the advantage that the triggering worked over long distances and even through walls or obstacles. In their basic function, these triggering systems only worked as a transmitter of a trigger signal for the flash. The power had to be set manually on the flash.

There are radio trigger systems that enable the transmission of data between the camera and the flash and thus the use of TTL automatics for flash control. Modern control systems can divide the devices into individual groups when controlling several flashes. Each group can be set individually in terms of the lighting intensity and the trigger time, so that very differentiated lighting scenarios are possible.

Application examples

At close range

Laterally diffusely illuminated
In-camera flash
Unleashed lightning at close range with an improvised light tent
  • Side lighting. In terms of design, this often has a better effect than the front flash, as it creates a more spatial effect.
  • the flash unit is to emphasize a part of the motif placed closer to the subject.
  • the flash unit is placed higher behind the camera. The result is a larger illuminated area and, depending on the environment, slightly softer light, which enables flashes with powerful wide-angle lenses , for example .
  • Use of reflectors . The flash is not aimed at the subject, but at a reflector. Depending on the reflector, this results in particularly soft light.
  • the use of walls or ceilings as reflectors for indirect flash. With colored surfaces (for example wood-paneled ceilings), color casts occur in the image. It creates a very soft , natural-looking light with a pleasant shadow effect . Flashing requires powerful flash units because of the scatter losses.
  • The flash unit is moved closer to the subject because it is too weak or too strong or is set up away from the subject.

Larger motifs

Nocturnal shot with the flash unleashed
  • Illumination of very large motifs, for example buildings, machines and rooms, by means of spatial and, depending on the motif, also temporally unleashed.
  • In earlier times, hall or banquet photography was also a special area, in which numerous flashes were used at the same time to uniformly illuminate the hall or the crowd.

See also

Web links

Literature (in German)

  • Roggemann, Hendrik (2011): Flashing unleashed. Creative photography with system flashes. 2nd edition Heidelberg, Munich, Landsberg, Frechen, Hamburg: mitp-Verlag. ISBN 382669144X
  • McNally, Joe (2009): Joe McNally's hot shoe diaries. Big staging with a small flash. Munich: Addison-Wesley. ISBN 3827328675