Fun Technique: Time to Get Flashy

By Jack Berglund

In this second in the series of fun techniques, you’ll be having so much fun you won’t realize I’ve tricked you into learning what rear sync flash is and how to use it.

Getting this effect is surprisingly simple, by setting your camera up correct and zooming whilst the shot is being taken. You’ll get the best results with a dedicated flash although you can have a crack with the one on your camera also with more mixed results.

First the ‘How’

The ‘why’ comes later, its more fun that way and as fun is in the title, we’re all about fun today:

  1. Set your flash to rear sync (sometimes called second-curtain) mode *see the note below if you’re unsure how to do this
  2. In manual mode, set your shutter speed to something around 1/2s – 1 s and your aperture close to wide open.
  3. The slower you go with the shutter speed the more pronounced affects you can get and the more time you have to apply the affect.
  4. Compose the start of your shot as you want. This will normally turn out to be the more ‘superimposed’ part of the picture
  5. Decide what you want the zoomed out ‘solid’ part of the image to be.
  6. Do a practice run without pressing your shutter. Go from the initial view to the zoomed out view. The reason for the practice run, is when you press the shutter, the mirror in your camera will be raised and you can’t see through the viewfinder anymore.
  7. Now for the real thing. Press the shutter and run through the zooming motion as before.

Adjust the speed you zoom at and the amount of time you rest on the initial view to adjust the strength of the affect. Can’t get the zoom complete in time? slow down your shutter speed. Speed up the shutter if the image is more blurry and abstract than you would like. Play around until you get the affect you want.  Try zooming in the other direction or delaying before you zoom to adjust the relative strength of the different image.

It may take a few attempts to get something usable but with a little practice you can get what you expect in the first or second go.

Note on setting rear sync flash:
On a Nikon, this is a setting on the camera – find the flash button (the one with the flash icon next to it), hold it down and roll your rear wheel until the words rear appear on the display. For Canon, this setting is sometimes on the camera and sometimes on the flash. If your using one of the entry level models (EOS 350D-1000D or ‘Rebel’ in the US), there is no way to set this in the camera – if your using your camera flash or a dedicated flash without this option you’re SOL – consider this when buying a flash (if you haven’t got one already). More info for Canon users:

Now the ‘Why’

Flash is bright (I’m all about stating the obvious today) so the image in view when the flash fires, registers much more strongly on the camera sensor than the rest of the time the shutter was open (assuming its dark).  This allows the flash to ‘freeze’ a subject even when longer shutter speeds are used.  You often want to use a longer shutter speed to make sure the background is visible even if its out of range of the flash but I digress – more on this in another post.  In this case, we are using the ‘freezing’ effect to get the appearance of two exposures.

By default, the flash will trigger at the start of the photo as soon as the shutter opens. The rear or curtain sync flash setting means that the flash will fire at the end of photo just before the shutter closes.  There is also a smaller flash at the beginning. The two flashes will freeze the image.  In this case the shot has been recomposed whilst the shutter is open, so the image from the first flash and the last flash are not the same – this is where the ‘double’ exposure effect comes from.

The control you have comes from the fact that not all of the image is caused by the flash.  The ambient light will contribute.  You can therefore vary the strength of the initial image by lengthening the shutter speed and pausing on the initial view before zooming.


Now!  As with most of photography, there is no substitute for trying these things.  The effect works best when its somewhat dark but otherwise there are no restrictions.

“What we have to learn to do, we learn by doing” -Aristotle

  1. Wow! this technique is cool. Will definitely try it tomorrow. ha! Thanks for the info! 🙂

  1. June 30th, 2010

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