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

Slow sync flash is a technique that is easy to apply and fun to experiment with. If you don’t know what it is, or how your photos can benefit from slow sync flash, keep reading to find out more.

What Is Slow Sync Flash?

A DJ wearing black surrounded by red smoky lighting.

Slow sync flash is 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 illuminated photo.

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

The flash in a slow sync setting is set to fire at either the beginning 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

Guitarist playing a live gig with lots of bright lights cleared around him.

The slow sync flash technique is great for capturing high-action moments, like dancing, live music, or sport without the distracting blur. You may commonly see nightclub or nighttime event photographers using this technique—they often spin, drag, or move their camera immediately after the flash pops.

It may look weird to see someone doing it, but this technique creates stunning results.

Photo of man throwing a ball in the air.

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

It is also used in fast sports such as mountain biking or car racing. However, you do need to be somewhat close to the subject to get the full effect, so it may be difficult to shoot certain sports with this effect if you don’t specialize in it.

How to Use Slow Sync Flash

While the technique remains largely the same no matter your chosen settings, it is important to understand which settings you need and then what happens when you change from one to the other.

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

First Curtain (Front Curtain) Flash

First curtain flash works by having the flash fire at the beginning of the exposure. This means the camera will capture the movement after the flash has fired. Using 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 pops, immediately move, spin, or tightly grip your camera, and you’ll benefit from the movement of the environment’s lighting. This can create light trails or ghostly images of other people as they move.

Second Curtain (Rear Curtain) Flash

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

Using a second curtain flash means all the movement will be captured before the firing of the flash, which freezes the subject in time. This setting works best when panning a subject—for example, a mountain biker doing a jump—to capture the movement in a freeze-frame.

In-Built Flash vs. External Flash

Lead singer of band leaning into crowd.

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

An external flash—sometimes called a Speedlight or flashgun—will offer you much more control than the on-camera flash. With a flashgun, you can set the flash power, focus in low lighting with infrared, and set different timing options for the flash to pop.

Using an external flash also gives you options like setting up off-camera flashguns to use flash lighting that comes from other sources. The flash doesn’t have to come from the direction of the camera to work. Even using strobe lighting will work.

If you use the in-built camera flash, you’ll have to be a lot closer to your subject to get the same effect, and this isn’t always possible. The power of a camera’s in-built flash is limited, and you often have no further control past turning it on.

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

The Best Camera Settings for Slow Sync Flash

person-holding-camera

Although there is no one setting that will always give great results, your camera settings (ISO, aperture, and shutter speed) should take care of the ambient lighting and general exposure, and the flash settings should be set according to the subject of your photo. It is also much easier to edit an underexposed image in post-production than an over-exposed one, so, if in doubt, always err on the side of lower flash power.

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

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

Each environment, subject, and other external factors will change your required settings. You should experiment to find out what works best for the shots you want.

Illuminate Your Photos With Slow Sync Flash

When you’re in a situation that requires using flash, employing the slow sync flash method is certainly going to make your photos pop. It’s a simple technique that brings the wow factor to an otherwise bland photo.

By using slow sync flash, you ensure your low light photography doesn’t get left in the dark and that all your important subjects are lit up and in focus as you intended.