Many speedlites have a Multi mode. In multi mode instead of firing just one flash per image the speedlite fires a burst of multiple flashes just like a strobe light. You can set the total number of flashes that you want and the frequency of flashes. The frequency is measured in Hertz (Hz) which is the number of flashes per second. Multi-mode is usually included on speedlites that have high speed sync capabilities since high speed sync also requires a quick burst of multiple flashed. When used with a slow shutter speed stroboscopic flash can also be used for creative effect to capture a series of movements within a single picture such as a dancer.
Calculating the Shutter Speed
During stroboscopic flash, the shutter remains open until the firing stops. Use the provided formula to calculate the shutter speed required to capture the full sequence of flashes:
Number of flashes / Firing frequency = Shutter speed
For example, if the number of flashes is 10 and the firing frequency is 5 Hz, the shutter speed should be at least 2 sec.
- Stroboscopic flash is most effective with a highly reflective subject against a dark background.
- Using a tripod and a remote switch is recommended.
- A flash output of 1/1 or 1/2 cannot be set for stroboscopic flash.
- Stroboscopic flash can be used with “bulb”.