Difference between Front Curtain and Hou Lian Synchronization in Flash Mode of SLR Camera

Generally, the shutter of 135 single-lens reflex camera has two shutter curtains, the first shutter curtain and the second shutter curtain. Also known as the Front Curtain and Hou Lian.

The basic action procedure is: press the shutter->; The curtain in front is open-> Film sensitivity->; Hou Lian is closed. The difference between front curtain synchronization and Hou Lian synchronization lies in:

Front curtain synchronization: the flash lights up at the moment when the first shutter curtain is opened.

Hou Lian synchronization: The flash lights up before the second shutter curtain closes. At present, SLR cameras use a shutter called "portrait", that is, the shutter in front of the photosensitive device opens and closes like a curtain. When it is opened, it is called "front curtain", and when it is closed, it is called "Hou Lian". When the flash flashes at the moment when the shutter is opened, it is called "front curtain synchronization" (slow), and when the flash flashes just before the shutter is closed, it is called "Hou Lian synchronization". The function of Hou Lian synchronization is:

The last image of the subject can be fixed on the screen under the slow shutter, so that the screen effect has a sense of movement and speed.