With a meniscus-type convex lens with a focal length of 50cm, the focus is at a distance of 50cm from the tip of the lens when the camera lens distance scale is at ∞. When the helicoid is extended, the focus will be closer. You cannot take pictures of subjects more than 33cm away. It is an old item, so there are scratches, dirt, and coating burns. The plastic case is warped, and the stopper claws do not work, so it opens easily.