Flash Sync

Alpha Tutorial :26 - Flash Sync

If you’ve never ventured into your camera’s built-in flash settings, you might be surprised by the different results you can get just by changing a few things. Depending on your camera model, you might be able to change none, some or all of these settings – the more advanced your camera, the more control you’ll be able to exert over its built-in flash.

Front Curtain Sync

When you set your flash to front curtain sync (or first curtain sync), you’re telling the flash to fire at the start of the shutter opening. Front curtain sync is the default setting for flash, and is used to fill shadows as well as freeze action at the moment you see it. When in automatic mode, front curtain sync has a minimum shutter speed set by default, so you can comfortably hand-hold the camera and still get a sharp image.

If you shoot moving subjects with front curtain sync and a slow shutter speed, you’ll get light trails which appear in front of the subject, making it look like the subject is moving backwards. That’s because the flash has fired and illuminated the subject at the beginning of its movement, and the slow shutter speed continues to capture the dimly-lit, still-moving subject.

Front Curtain Sync

Rear Curtain Sync

Unlike front curtain sync, setting your flash to rear curtain sync (or second curtain sync) tells it to fire at the end of the shutter opening, just before it closes. Together with a slow shutter speed, rear curtain sync lets you capture more of your ambient light and background, as well as your flash-lit subjects.

You have to tell your subjects not to move however, as well as have your camera steady, because the slow shutter speed can result in blurry images. However, this blurring can be used intentionally to create streaks which trail behind your subject, conveying a sense of speed.

Rear Curtain Sync

Slow Sync

Depending on your camera model, you might have the option for both rear curtain and slow sync flash. Like rear curtain sync, slow sync tells the camera to expose for the ambient light, so you capture more of the surrounding areas not lit by your flash. Because you use flash in a dim environment, this can result in very slow shutter speeds.

The main difference with rear and slow sync modes is when you get to choose them; slow sync is usually available in P and A modes, where you do not define the shutter speed, and it can be either slow first curtain sync or slow rear curtain sync. In S and M modes you can select either first curtain sync or rear curtain sync, then set the shutter speed to be as fast or slow as you want it.

In some cameras, setting the camera to rear curtain sync automatically activates slow sync, but setting slow sync does not always activate rear curtain sync.

Recommended flashes:

HVL-F60
HVL-F60

Experience a lightweight, powerful flashgun with a flash guide number of 60 (GN60), 1200 lux LED, and quick shift bounce for expertly lit photos every time.

HVL-F20
HVL-F20

For more power than your built-in flash, this compact external flash has a flash guide number of 20 (GN20), multi-flash effect options and wireless capabilities.