Flash synchronization

As flash sync or sync flash automatic synchronization of firing a flash unit is denoted by the end of the closure. It ensures that the closure during the duration of the flash reveals the full movie window.


There are three different methods of flash synchronization.

  • M- synchronization
  • X-sync
  • FP synchronization

This distinction is independent of the type of transmission used for the signal. It is merely names for unified processes and technical requirements or conditions. They are both wired and used wirelessly.


There are, by definition, no dependencies on specific contacts or connectors. The manufacturers of the cameras implement these methods for various reasons, only part of their equipment or offer it only in certain price ranges.

Modern flash units of the used camera systems simplify the flash photography by numerous automatic functions and enhancements such as wireless remote flash, rear-curtain sync, and stroboscopic flash. It is possible to use shutter speeds that are much faster than the flash sync speed. Because of this very short synchronization times a fill-in flash is possible in almost any situation.

If the sync socket used to connect studio or Special flash units, no automatic functions of flash units can be used, as this does not allow transmission of additional control information. FP - synchronization can not be used in this case. Through the use of special adapters for the accessory shoe or wireless control with special master flash units or dedicated channels, this problem is solved.

M- synchronization

The M stands in this case for 'medium time', in this type of sync, the flash will trigger even before the shutter is fully open. Since the chemical process of combustion must be set in motion only, so ensuring that the shutter of the camera is fully open when the maximum brightness of the glass bulb flash is reached. This is the prerequisite for flashing with central locking at exposure times shorter than 1/30 second when using flash devices with flash bulbs.


The X in the name refers to the noble gas xenon, which comes in the electronic flash tubes used. The ignition of the flash is performed after opening of the closure. In this method, the flash sync speed is 1 /60 sec and 1/ 300 s in some digital cameras with a smaller sensor. Cameras with focal plane shutter in small picture format, to 1/ 500 s These values ​​depend on the structure of the shutter and the design of the camera -dependent. For cameras with central locking shorter sync speeds up to 1/2000s one are possible.

Provided that the lighting period of the flash bulbs is observed, it is also possible to use it together with an X- synchronization. The fastest flash sync speed that can be achieved with flash bulbs, between 1/30 s and 1/ 60 s

Normally, the X-sync by the center contact on the accessory shoe of the camera is realized. For applications in the photo studio even further away with flashes can be controlled via an extra connection. Older cameras with additional FP- synchronization either have a switch for the synchronization on or separate connectors.


The short-time synchronization or high-speed synchronization (HSS ) has been developed to allow flash photography with exposure times that are shorter than the flash sync speed. This mode is also sometimes referred to as a (Super) FP mode or FP mode, where FP comes from the English and stands for focal - plane shutter ( focal plane shutter ). This synchronization is tuned to slow-burning, cool burning largely consistent light output flash bulbs such as Sylvania M3 (WZ ). The look-alike M2 from the same manufacturer is unsuitable because they burn off quickly and not uniform.

The technique

At shutter speeds below the flash sync speed focal plane shutter is fully open at any time. Since the flash time is significantly shorter than the shutter speed, it came on the shared area of ​​the medium to a partial exposure. By placing multiple flashes in a row ( no strobe ) or by a prolonged delivery of a single flash during the entire shutter speed is evenly flash illumination of the entire medium. However, both methods have a considerable reduction of the flash output result because the flash must be fired more than once or over a longer period and much of its power is blocked by the shutter curtain. Most camera manufacturers realize this flash mode with the strobe flash. Olympus uses the extended single flash at its digital e- system to some extent. This rapid movements are mapped by a wiping effect corresponding to the movement, while frozen by the strobe effect of the movement appears. The single flash thereby enables a more dynamic photo. In stroboscopic flash, it can happen that are not fully reflected in unfavorable overlap between the exposure and motion segments partial movements. In both techniques, the movements according to the exposure time sections are shown slightly offset.


By reducing the shutter speed, the aperture can be opened further. Thus, a targeted influence on the depth of field is also possible with flash photography.

Suitable high-speed sync is also designed to Brightening subject in very bright ambient or in backlight conditions. Here, a fast shutter speed to prevent overexposure to the environment.

Due to the already mentioned reduction of the flash output, the short-term synchronization is not suitable for distant subjects.