Macro lens Focal Length

The distance (measured in millimeters) from the optical center of a macro lens to the camera sensor, which dictates the working distance between the lens and the film. For camera scanning, a longer focal length (typically 90{mm} to 105{mm}) offers significant advantages over shorter 30\text{mm} or 50\text{mm} lenses. It provides more physical space under the camera to comfortably manage film holders and masks, minimizes the risk of casting shadows over the film, and allows the copy stand to operate at a more ergonomic height.