The 70's and 80's were plentiful with lenses for 35mm slr's. Companies like Cosina made dozens of lenses under various brand names for dozens of dept stores, camera stores and other manufacturers. Gemini is one of those many brands. This is a decent lens which produces good usable images from f4.5. Contrast is good. Colors are accurate. Fringing is well controlled. It is a well made lens. Focus dampening is good. Push-pull zoom action is smooth. Sharpness is good wide open.