I have this lens too - and like you have tried trees as a subject to conceal the distorted image. I've noticed some lateral colour that can be removed from scanned images in PS. Did yours come with a full set of filters? Mine had just the UV. A filter needs to be used at all times or the lens won't quite focus to infinity. I found some 40.5mm contrast filters for b/w and had the mounts thinned on a lathe to allow clearance for the camera's mirror. I also made a R72 IR filter using a stepping ring and a 43mm glass. The fisheye distortion can be removed with software giving a 2:1 aspect ratio. I have seen photos of a number of these lenses and the serial numbers all seem to start 11000. Mine is 11020 - maybe that means it's the 20th one made? What is the serial number on yours?
Originally Posted by philosomatographer