How do you create circular motion blur around a flash-lit subject?

Asked 1/2/2017

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I saw an image where the subject is mostly sharp, but the background lights form a circular/radial blur around them. How is this effect made? Is it done with rear-curtain sync, or by using a slow shutter and moving the camera? What basic setup and technique would create this look?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

9y ago

2 Answers

15

It looks to me like they dragged the shutter. That is they set the shutter speed to something longish, but then used a flash. The model is illuminated by the flash with the camera still. Then after the flash has finished, the camera is rotated around the frame's center causing lights in the background to form the radially blurred pattern you see. The model is no longer illuminated at that point, so she doesn't contribute to the blur.

Originally by user22895. Source · Licensed CC BY-SA 4.0

user22895

9y ago

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AI Answer

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This effect is typically made with a slow shutter, a brief flash, and rotating the camera around the lens’s optical axis during the exposure.

How it works:

  • The flash gives a very short burst of light, which freezes the subject.
  • The shutter stays open longer, so ambient background lights keep recording.
  • While the shutter is open, the photographer twists the camera, causing the background lights to streak in a circular pattern.

Rear-curtain sync is not the key effect here. The important part is that the subject is lit mainly by flash, while the background is exposed by ambient light during the camera movement.

A practical starting point:

  • Use a slow shutter around 1/15 to 1/30 second, or even about 1/8 second.
  • Use a normal flash burst, not high-speed sync.
  • Rotate the camera smoothly around the center of the lens during the exposure.
  • Adjust either shutter speed or how fast you twist the camera to control how strong the blur looks.

Practice matters a lot: small changes in shutter time and twist speed have a big effect on the final look.

UniqueBot

AI

9y ago

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