In general, focal plane shutters, which are used with single-lens reflex cameras, use two mechanical shutter curtains: front and rear curtains located in front of the image sensor (lens side).
In products with translucent mirrors or in mirrorless cameras, the shutter stays open during live view before shooting. When the shutter button is pressed, the front curtain closes once, and then opens to expose the image sensor to light for a given exposure time (shutter speed). Then, the rear curtain closes when the exposure time finishes.
NOTE: You may hear the shutter sound twice when shooting because of this operation, one from the front shutter curtain and the other from the rear shutter curtain, depending on the shutter speed.
In the electronic front shutter curtain function, operation of the front shutter curtain is avoided through electronic control of the image sensor. Instead of mechanical operation of the front shutter curtain, the exposure is started electronically by the image sensor and finished by closing the rear shutter curtain.
NOTE: You hear the shutter sound only once in this operation because only the rear shutter curtain operates mechanically.
IMPORTANT: Set Electronic Front Curtain Shutter to OFF in the following situations.
- When shooting at a fast shutter speed with a large-caliber lens attached
If you shoot images with Electronic Front Curtain Shutter set to ON, images may blur or be cut off, depending on the subject or shooting conditions.
- When shooting at a fast shutter speed
If you shoot images with Electronic Front Curtain Shutter set to ON, the brightness of the image may be uneven, depending on the shooting conditions.
- When using Minolta/Konica Minolta lenses
If you shoot images with Electronic Front Curtain Shutter set to ON, the camera may not get the proper exposure, or the brightness of the image may be uneven.
By shooting with the electronic front shutter curtain function, because there is no mechanical operation of the front shutter curtain, you can shoot images with a short release time lag, the time after the shutter button is released until exposure is started.