A camera having a shutter button, a photo sensor array, an anti-shake module controlled by an anti-shake enable signal, and a mechanical shutter. By pressing the shutter button, a first operation and a second operation are provided to trigger an auto-focus enable signal and an image exposure control signal, respectively. The anti-shake enable signal is enabled when the auto-focus enable signal has been triggered and the image exposure control signal is disabled or has just been triggered. The photo sensor array performs image exposure according to the image exposure control signal. The mechanical shutter is disabled and closed after the image exposure control signal is triggered for exposure period.