Photography has an expression technique that lets a person see the main subject closely by shading off background to put the main focus on the main subject, such as a person. However, its depth of field is deep and cannot satisfy the demand of the user to adequately shade off the background of the subject because almost all digital cameras have an imaging element only 1/5 size of that a film camera. Therefore, in this study, a method was developed to change the depth of field of digital camera images to that of film cameras by Using firmware.