What's the difference between front curtain synchronization and Hou Lian synchronization?

Front curtain synchronization and Hou Lian synchronization are two different forms of slow synchronization. Slow synchronization means that when shooting portraits at night, the flash is used to ensure the correct exposure of the characters, and the slow shutter is used to ensure the correct exposure of the background night.

Front curtain synchronization means that after we press the shutter, the flash will start flashing when the shutter is opened, and it will automatically turn off when the specified output light is reached, which is generally shorter than the shutter time. The shutter is exposed normally according to the length of time you set. Use "front curtain synchronization", first flash to make the subject bright, and then expose for a long time to make the background brighter. Mainly used for static objects.

Hou Lian synchronization indicates that after we press the shutter, the shutter opens normally, and the flash flashes when the shutter closes. It is mainly used to shoot objects with relative movement tendency and activities, such as people, moving vehicles, animals, sports and dance themes. To show the dynamics of light and shadow and keep the theme clear at the last moment.