Events photography

What is slow sync flash in photography? How and when to use it

How can you use flash creatively in your photos? Quite easily, in fact.

Slow sync flash is a technique that’s easy to apply and fun to experiment with. If you’re not sure what it is or how your photos can benefit from slow sync flash, keep reading to learn more.

What is slow sync flash?

Slow sync flash occurs when you take a photo with a long shutter speed and a burst of flash to freeze a moment in the exposure. This technique can create different results depending on how you use it. The flash fires faster than any shutter speed, so it freezes the action, and with a longer exposure it creates a much more dynamic and lit photo.

Using a slow shutter speed captures motion, but without flash it would just create a blurry image as the subject moves through the frame. With a burst of flash, it captures both motion and frozen time in a single image, giving you the best of both worlds.

The flash in a slow sync setting is set to fire at the start or end of a long exposure. Each timing creates a slightly different result, and both have their individual uses.

When to use slow sync flash

The slow sync flash technique is ideal for capturing high action moments, such as dancing, live music or sports without the distracting blur. You can often see night club or night event photographers using this technique – they often turn, drag or move their camera immediately after the flash fires.


It may seem weird to see someone do it, but this technique creates amazing results.

Slow-sync flash is best used in similar environments where flash is required: low-light situations. However, if you’re capturing the movement of a close subject in the daytime or in brighter lighting, you can still use slow sync flash.

It is also used in fast sports like mountain biking or motor racing. However, you need to be quite close to the subject to get the full effect, so it can be difficult to shoot certain sports with this effect if you’re not an expert in it.

How to use slow sync flash

While the technique remains largely the same regardless of which settings you choose, it’s important to understand which settings you need and then what happens when you switch between them.

Your flash settings are the most important to know for this technique. You will need to use either the first curtain flash (sometimes called the front curtain flash) or the second curtain flash (also called the rear curtain flash).

First curtain flashing (front curtain)

First curtain flash works by firing the flash at the start of the exposure. This means that the camera will capture movement after the flash fires. Using the front curtain flash is best in portrait situations where you want to use ambient lighting as a decorative element.

Press the shutter, once the flash appears, move, rotate or firmly grip your camera immediately, and you will benefit from the movement of environment lighting. This can create light trails or ghostly images of other people as they move.

Second curtain flash (rear curtain)

The second curtain flash is the opposite of the first curtain flash; you can expect the flash in a second curtain setting to fire at the end of an exposure, rather than at the beginning.

Using a second curtain flash means all movement will be captured before the flash fires, freezing the subject in time. This setting works best when panning across a subject (e.g. mountain biker doing a jump) to capture movement in a freeze frame.

Built-in Flash vs External Flash

Should you use your camera’s built-in flash or will you benefit more from an external flash? You can use the camera’s pop-up flash in some cases; however, it is largely advantageous to use an external flash.

An external flash, sometimes called flash or flash gun, will give you much more control than the flash built into the camera. With a flash, you can adjust the flash output, focus in low light with infrared, and set different timing options for the flash to fire.

Using an external flash also gives you options like setting up off-camera flashes to use flash lighting from other sources. The flash does not have to come from the direction of the camera to work. Even using strobe lighting will work.

If you’re using the camera’s built-in flash, you’ll need to be much closer to your subject to achieve the same effect, and that’s not always possible. The power of a camera’s built-in flash is limited, and you often have no additional control after turning it on.

Some cameras may not offer a rear curtain flash option in their built-in flash, further limiting you in how you can use the slow sync flash technique.

The best camera settings for slow sync flash

While no one setting always gives great results, your camera settings (ISO, aperture, and shutter speed) should take ambient lighting and general exposure into account, and flash settings should be defined according to the subject of your photo. . It’s also much easier to edit an underexposed image in post-production than an overexposed image, so when in doubt, always go for a lower flash output.

Photos of close subjects should use lower flash output. If the subject is further away, use a higher flash output. If you’re in a position where you can experiment, change your flash power settings from full power (1/1) to low power (1/128) so you can visually see what a difference it makes.

In general, an ISO between 200 and 1600 should work, with a relatively wide aperture. Despite the focus on long exposure in slow sync flash, your exposure doesn’t need to be longer than 1/4 second.

Every environment, subject and other external factors will change your required parameters. You should experiment to find what works best for the photos you want.

Brighten up your photos with slow sync flash

When you are in a situation that requires the use of flash, using the slow sync flash method will definitely make your photos stand out. It’s a simple technique that brings the wow factor to an otherwise bland photo.

By using slow sync flash, you ensure that your low-light photographs don’t stay in the dark and that all your important subjects are lit and in focus the way you want them.

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