1. A method of performing an automatic focus function upon a single specific movable target object in a real-time manner, the method being applicable to a photographic apparatus, which comprises a photographing button and a lens and has the automatic focus function, the method comprising: photographing a reference image, before the photographing button is pressed, of the single specific movable target object through the lens to generate a feature image of the single specific movable target object; storing the feature image of the single specific movable target object in a database; capturing a real-time image within a field of view (FOV) of the lens; comparing images of a plurality of image areas of the real-time image with the feature image of the single specific movable target object for identifying an image area corresponding to the feature image of the single specific movable target object and identifying, after the photographing button is pressed, a location of the single specific movable target object, wherein the feature image of the single specific movable target object is identified within the real-time image and corresponds to at least a portion of a dressing characteristic of a person, an accessory characteristic of a person, a non-physiological possession characteristic of a person, or an animal characteristic without including human characteristic; and performing automatic focus of the lens, after the photographing button is pressed, upon the identified location of the single specific movable target object.