This Canon XI 433mm f/6.7 x-ray camera machine lens was Made for Picker Corp. The diameter of its nose is 3'' and its rear is 4''. The diaphragm is exposed on the backside. It is not missing a rear element - this is the design of the lens. There is a small amount of fungus around the outer perimeter of the front element grouping and there are a few light haze spots inside of the rear grouping. Its aperture adjustment is smooth and its glass is free of any separation to its elements.
