The front vertex focal length: -49.60 mm. Back vertex focal length: 27.75 mm. The actual focal length: 52.49 mm. The distance from the first to the last surface: 31.74 mm. Light diameter of the first surface - 29.0 mm.
Light diameter of the last surface - 22.0 mm. Resolution (0 mm / 10 mm / 20 mm): 39/29/24 lines / mm. Resolution of TU (center / edge): 30/14 lines / mm. Light transmission coefficient: 0.81.
Please ask questions, I will be happy to answer! The serial number on the lens may differ! The lens is in good condition! Optics clean, without scratches, without fungus! Otherwise we can't guarantee availability of it. I take our feedback seriously. I'll try do everything we can to resolve the issue.