This lens was manufactured in the mid-80s by Cosina and sold under various brand names (Cosina, Vivitar, Exacta and even Carl Zeiss Jena). It's rumored to be very sharp. Despite it's macro designation, it's not really a macro lens, but it focuses really close for a wide angle: its MFD is just 15 cm from the image plane, which is impressive. My copy of the lens is labeled as Exacta and comes in the Canon FD mount. I bought it for about $12 to replace my late Tokina 24mm f/2.8 which drowned in the Dnieper 3 weeks ago. Actually I wanted to buy the Canon FDn 24/2.8, but couldn't find one in time for upcoming holidays. I will be mainly using this lens in my film setup, but also did a couple of test shots on my GH2 to see if it's really good. What can I say? I'm very impressed. The lens is already sharp (but slightly hazy) at f/2.8, and at f/4 it's very sharp. This one was shot at f/8 to achieve reasonable DOF: Full size: http://photo.torba.com/images/pavel.urusov/f/Po4ln57a97OYKhHWJunm.jpg And this image shows sharpness in the center of the frame at f/4 (this is 100% crop): DMC-GH2    ---       f/1.0    1/15s    ISO 160 The bottom of the "GIII QL" badge is soft because of limited DOF, not because the lens is soft.