Helicon Focus is a program for focus stacking. Focus stacking is a post-processing technique that enables you to extend the depth of field beyond what is available in one shot. First take several shots of the same scene; then let the program blend them together into one image with an extended depth of field. For each shot, you focus your lens on a different part of the object. The resulting series of photographs is called a "stack," and the process of merging them into one image is called "focus stacking."