Technical Slow Sync Flash: What You Need to Know

This is a flash shooting technique, in which the shutter opens for a relatively long time, to create special motion effects for the photo.

Slow Sync Flash creates special motion effects for the photo to emphasize the subject. Photo: Digital Photography School.

Slow Sync Flash (slow sync flash) is a flash shooting technique, in which the shutter opens for a relatively long time, to create special motion effects for the photo. Here, background light is the factor that contributes to high contrast with the subject. Besides, fast movements in the frame recorded during the exposure will create "paths" to emphasize the subject.

Need to distinguish Slow Sync Flash with shooting method using pure flash, in which the synchronization time between flash and shutter is not too long (about 1/25 seconds or less). This traditional method is activated in the Auto mode of the camera when shooting in low light environments. The motion is almost frozen immediately, the whole image will record the main object and the background for a short time so it does not reproduce the "path" effect like Slow Sync Flash technique.

Some cameras (typically DSLR types) support manual slow flash sync control. You can completely adjust the exposure time and flash brightness to suit your intended use. Many compact cameras allow only limited control in night mode (Night mode) or party mode (Party mode).

Here are some modes.

1. Synchronize before and after.

Rear Curtain Sync technique freezes motion at the end of the exposure process. Photo: Digital Photography School.

Rear Curtain Sync (after sync): The flash lights up at the end of the exposure process. Thus, immediately after pressing the shutter button on the camera body, the shutter will open for quite a long time to receive backlight and record movement. At the end of this process, the flash is activated to reveal the main subject. In essence, this process is a clever combination of long exposure with shutter and short exposure using flash.

The Front Curtain Sync technique records the sharp image of the subject at the beginning and movement of the object during the shutter opening. Photo: Seattlepi.

Front Curtain Sync (previous sync): The flash lights up at the beginning of the exposure process, ie when the shutter button is pressed. After that, the shutter will open for a long time to perform the same function as in Rear Curtain Sync. This technique can be used when you want the flash to freeze the subject's rapid movements from the beginning. The resulting image will record the sharp image of the subject and the movement of the object during the shutter opening.

2. Function of tripod

Tripods are needed in most low-light shooting situations. Photo: Mrgadget.

Even when holding the camera firmly in your hand, very light vibrations caused by the wind also make the whole picture use blurry slow flash sync technology. Exposure for at least 1 to 2 seconds requires the use of a tripod. In particular, to limit the vibration caused by pressing the shutter button, you should invest in a camera controller (wireless or cable connected to the computer). Without conditions, the most common remedy is to place the camera on a tripod, start the self-timer (about 10 seconds) and let the machine automatically complete the remaining steps.

You can use the hand to hold the device and create very special effects. Photo: Digital Photography School.

In some cases, using a hand to hold the camera creates a very special effect. For instance,, you are attending a party and want to record the moment of the dancer. In this case, it is difficult to use a tripod and it is imperative to keep the camera on hand. The slow flash sync technique will produce a very cool image with the image of the subject clearly visible and the background is a brilliant spotlight blurred into streaks.