The Schneider 138mm Diopter Full +3 Gen2 lens attachment reduces near focus distance, allowing you to capture macro images without using a special macro lens. This is done by increasing the magnification while the field of view decreases, but the depth of field is retained. This filter is a suitable option for reducing the MOD of anamorphic and zoom lenses. The +3 strength is a reciprocal of focal length in meters.