Replicating the Imagon
I set out to replicate this lens, not only to demonstrate the principle, but also because I really wanted to add this capability to my bag of tricks. I decided to use a 75 mm f/ 1.5 achromatic lens from Surplus Shed that I already had mounted and ready to go. It is mounted in recycled filter rings and has a 52 mm thread which conveniently fits my K2 ring which attaches to my bellows. The aperture disks fit between the lens and the K2 ring.
However, this simple configuration would not focus to infinity. So, I added two negative meniscus lenses in front of the 75 mm achromat. This was done to provide enough back focus so that I can reach infinity focus with this lens on my bellows. This results in a lens with a focal length of approximately 110 mm and an aperture of about f/ 2 wide open.