1. A mobile terminal, comprising: a camera including a first camera and a second camera; a touch screen; and a controller configured to: cause the touch screen to display a first preview image being received from the first camera with a first focal length, detect at least one facial object included in the first preview image, cause the touch screen to display a second preview image, being received from the second camera with a second focal length shorter than the first focal length, including the at least one facial object based on the detection with respect to the at least one facial object, execute different functions for different images to which a preset type of touch is applied, wherein the preset type of touch includes a pinch-in touch and a pinch-out touch, when the pinch-in touch is applied to the first preview image while the first preview image is displayed on the touch screen, switch a main camera from the first camera with the first focal length to the second camera with the second focal length, when the pinch-in touch is applied to the second preview image while the second preview image is displayed on the touch screen, display the first preview image and the second preview image together, set both the first camera with the first focal length and the second camera with the second focal length as the main camera and capture the first preview image and the second preview image when the pinch-out touch is applied to the first preview image while the first preview image is displayed on the touch screen, and when performing a camera switching function by the pinch-in touch or the pinch-out touch, control not to zoom-in or zoom-out the first preview image in response to the pinch-in touch or the pinch-out touch.