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On of the cooler effects you can do with a camera is to combine motion with a flash.  This is called the flash blur.

In a nutshell, you use a long shutter to create the effect of the motion, and then freeze the action with a flash.

Normally, the flash goes off at the front of the shutter cycle, or as soon as the shutter opens.  In the case of the fire photo above, I used what is called a rear curtain sync.  This means that the flash goes off at the end of the shutter cycle, or just before the shutter closes.

Sometimes this can get a little confusing, so think of it this way…  For the sake of this illustration, lets expand the shutter cycle to 10 seconds.  We press the go button and the shutter opens.  One, two, three, four….. nine, ten, the shutter closes.  When your camera is set to “normal,” or front curtain sync, the flash is triggered on the one count.

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Now imagine the camera is on a tripod, and a man is walking from left to right across the frame.  As soon as we see him in the lens, we press play, and open the shutter.  One (the flash goes off and freezes a bright, clear impression of the man on the left side) two, three, (the film is continuing to burn his image as he streaks to the right,) five, six, seven, (the man is still moving and his image is still being blurred as he walks.  Nine, ten (the shutter closes.)

So what does this effect look like?  You have your subject frozen on the left side, but then a streak rushes out in front of the man in the direction where he is walking.  The fact is that this looks weird.  The photo breaks the laws of physics.  If we want to give the feeling of speed or motion, we want the streak to be trailing the subject.  How do we do this?  We use the “rear curtain sync.”

What we want to do is to burn the image of the walking man as he moves across the frame, and then freeze him at the end of the shutter cycle.

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Set the camera to “rear curtain sync,” and then go for it.

Now open the shutter.  One, two, three, the man is being blurred.  Five, six, seven, he continues to be blurred.  Nine, ten (flash, the strobe goes off, the shutter closes.)

Basically all we are doing is freezing our subject at the end, rather than the beginning.

There is a pretty detailed post about how we shot the MTB rider shot in another post (seen above) if you are interested in reading more.

Its a cool effect, and worth experimenting with.  Id love to see some examples if you experiment with the technique, so eMail em to me and I will post em if you feel like it.

Give it a try.

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