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How to Use Photographic Rear-Curtain Flash Sync

I enjoy photography and have been doing so professionally and independently for over 30 years.

Used by permission from the artist

Used by permission from the artist

What Is Flash Sync?

According to Wikipedia:

"In a camera, flash synchronization is defined as synchronizing the firing of a photographic flash with the opening of the shutter admitting light to photographic film or electronic image sensor. It is often shortened to flash sync or flash synch.... Some modern electronic cameras include the ability to fire the flash just before the closing of the shutter, so that moving objects will show a streak where they came from and a sharp image where they were at the end of the exposure, useful for moving objects to convey a sense of speed. This mode is called either rear-curtain sync or 2nd-curtain sync."

Most modern cameras allow various degrees of creativity with a flash unit. This creativity allows a photographer to experiment and often capture quite exceptional shots.

One of the most creative techniques is to set the flash to fire at the end of the shutter cycle—firing when the shutter is about to close. This is usually called rear-end or rear-curtain flash synchronization.

The technique can create images that show trails of light that seem to follow the movement of the subject from the moment the movement starts to when it ends.

The best effects are those that show the trails when the movement starts while the firing of the shutter freezes the action and creates a sharp clear image that appears to be followed by lights traits.

This in essence adds the effect of movement and can show an audience exactly how the action proceeded.

This is basically accomplished by using two types of lights; one is ambient light that allows for the photographer to focus and follow the movement and the other light source is the flash that freezes the action.

The scene is best done in a darkened studio so that you can have total control of the lights since the ambient light cannot be so strong that it creates "frozen frames" of the subject as it moves. You also have to have a shutter speed that is just slow enough to allow for the movement to blur while waiting for the flash to freeze it.

Some of the best setups are to choose models who are dressed in eye-catching or vivid attire, preferably one that flows, and have her dance or create ballet-type movements.

My preference has always been toward red or vivid blue dresses as they seem to work very well at calling attention to themselves thus to the image.

In other words and to be more technical: using your flash alongside another light source and with a long shutter drag means that you are in reality utilizing two or more light sources and whatever is in front of the camera and being illuminated will show in the final image or in a single exposure.

So when the flash shoots and since it is usually the stronger light source, the subject that receives the flash burst will be captured and recorded on top of the rest of the image.

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CC BY 2.0

CC BY 2.0

The technique is also very useful for some sports photography where the image benefits from showing motion. However for the technique to work best the ambient light cannot be very strong.

Good scenes are those that occur during dusk or in heavy wooded areas where the flash can illuminate and freeze the action.

This is very similar to panning, where you follow the moving subject with the camera while the shutter is still open. However panning seldom produces as clear and crisp images as using the rear-curtain sync method.

The good thing about using rear-curtain flash sync is that you get the best of both worlds; images that show some blur and crisp and clear images, all in the same frame. Better than panning and easier too and you really do not have to do so many trial and error shots until you get the technique right.

Further Reading

  • Slow Sync Flash - Digital Photography School
    One camera function that can be a lot of fun to play with (and that can get you some interesting results) is slow sync flash. Low Light Photography Options When shooting with a subject in low light situations you generally have two options; either

© 2013 Luis E Gonzalez


Luis E Gonzalez (author) from Miami, Florida on December 09, 2014:

HandyHelper: Thank you

HandyHelper on December 09, 2014:

I love the combination of sharp and blurred pictures. They look spectacular. This may be the closest possibility of catching the movement into still photo. It opens many creative possibilities too. Thanks!

Luis E Gonzalez (author) from Miami, Florida on November 19, 2013:

teaches12345: Thanks, glad you liked it

Dianna Mendez on November 19, 2013:

What a great way to enhance photography. I only wish I had the equipment to make this happen. Thanks for the education.