Photography basics: What is flash sync speed?

Learn more about flash sync speed and how it can affect your photos when you dive into the world of flash photography.

In flash photography, brief “pops” of artificial light can be used to brighten a scene that would otherwise be underexposed. But using flash isn’t as simple as flicking on a button; you’ll need to take into account shutter speed to have a correctly exposed image. Let’s look into what flash sync speed means and how it affects your work.

What does flash sync speed mean?

Before we explore more about flash sync speed, let’s first talk about something called a focal plane shutter. Most mirrorless and DSLR cameras operate with this type of shutter.

Basically, a shutter is made up of two horizontal “curtains.” When you take a picture, these curtains move in order to expose light to the camera’s sensor. The top curtain moves first to allow light in, while the bottom curtain follows closely behind to shut light out. Your shutter speed determines how quickly these curtains open and close.

Now, imagine taking a photo with a flash. The flash sync speed is the fastest shutter speed in which your camera can successfully process the flash. This sweet spot puts them “in sync” with one another.

The limitations of sync speed explained.

If your shutter speed is set really high, you won’t have a fully open window when those curtains move. This is important because when your flash sends out that single burst of light, it might only expose a small section of your photo before that second curtain comes up. As a result, you’ll see a black band across your photo from the shutter closing too soon.

Every camera will have what’s called a maximum shutter speed sync (which can be found in your camera’s user manual). This is the fastest shutter speed you can set to avoid these black bands. To learn more, discover great photo tips for experimenting with different niches of photography.

Explore what more you can do with Adobe Lightroom as you start shooting flash photography.