Using Your On Camera Flash Part IV

Note:  Kirk is "the Affordable Full time Professional Wedding Photographer Winsdor,  Ontario".  Here is the Link to KW Masters Photography.

Introduction:

Your Canon 580 EX II or equivalent is an amazing Flash Gun!  To date, we have looked at using it in TTL and manual mode.  Today we will look at using the Multi Mode setting.

What is the Multi Mode Setting?

This operating mode allows you to set the 580EX II to fire
repeatedly, during a single long exposure. You can set the firing
frequency (flashes per second, expressed as Hz, from 1-199 per
second), the total number of flashes during the exposure, and the
flash output. Note: Although any wireless flash settings you have
made will remain active while you are in Multi Mode, the results
can be unpredictable. It's best to test the exposure and effects
before combining wireless flash with Multi Mode.

Calculating the Shutter Speed

During stroboscopic flash, the shutter must remain completely
open while the Speedlite is flashing and close as soon as the
flashing stops. Use the formula below to calculate the necessary
shutter speed.
No. of flashes / Firing frequency = Minimum shutter speed

For example, if the number of flashes is 10 and the frequency is 5
Hz, the shutter speed should be at least 2 seconds.

When to Use Multi Mode

Typical application is single-frame chronophotography - capturing several phases of movement on same photo. So a suitable situation is where some interesting movement occurs. If the subject stays in one place during its movement (e.g. a dancer spinning), you can slowly pan your camera instead to have different phases recorded on different locations in your frame.

A variation of this is capturing the same subject from several angles on single frame by moving your camera around it while the flash is strobing. The subject is still, but the camera is moving. So a suitable situation is when there are several views of the same subject you want to show simultaneously.

For these techniques, dark background and light-colored subject tend to give better results.

Another case would be when you want to imitate multiple flashes with one flash and you need constant frequency to form a pattern - when your flash is moving at constant speed this will give you flashes at equal distances. If you don't need constant frequency, manually triggering the flash (e.g. with "Test" button) will give you more control over the outcome.

Summary:

As you can see, using this mode requires considerable planning and layout of the shot.  But it can be challenging and fun to use.

Reference Video

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