Digital Camera Shutter Synchronization

The camera's shutter is equipped with a synchronization mechanism that closes a flash shooting circuit. It's necessary that the maximum intensity of the flash is enough when the shutter is completely open. If we have to connect an external flash to our camera, two options are possible: a cable connection and or a synchronization clamp. A type of flash that is mounted directly on the camera's clamp, which normally has contacts for the synchronization and automatic exposure regulation. Larger portable flashes and studio equipment are connected with a cable to the camera's terminal. In case that the clamp on our camera doesn't have synchronization contacts and the flash doesn't have a cable connection, we can use an accessory clamp with contacts that connect to the camera with a cable. The electronic flash is instant, since the flash is no longer than 1/500 of a second, and reaches it's maximum intensity at the moment when the circuit closes. The synchronization happens in the moment when the shutter is completely open, and is indicated with the letter X. In older camera models there is another type of synchronization, for lamp flash, where the circuit closes instants before the shutter opens to give time for the lamp to reach it's maximum temperature. This type of synchronization is indicated with the letter M and is incompatible with electronic flash, since the flash will happen before the shutter opens. When the camera allows an option between X mode and M mode there is an option we have to pay attention to because an error at this point can be unattended and ruin many photos.

The Shutter and Synchronization

We saw that one of the differences between the central shutter and the curtain shutter is that the first is completely open for an instant, were as the second, for high speeds, makes and exposure through a crack: a flash in these condition will only cause a partial exposure of the image. While with a central shutter we can synchronize the flash to any shutter speed , with a curtain shutter there is a limit of the shutter speed we can use. This limit is called synchronization speed and is the fastest value of the scale with which it Is possible to synchronize a flash. Any speed slower is also synchronized with the flash.