Focal distance is a term used in photography that refers to the distance between the camera lens and the camera's image sensor when the lens is focused on a particular subject. The distance is used to determine the sharpness and clarity of the subject in the photograph. Synonyms for focal distance include focal length, focus distance, and focusing distance. Other related terms that can be used interchangeably include object distance, image distance, and lens-to-image distance. These terms are essential in understanding the technical aspects of photography and are used by photographers to achieve the desired effect in their images.