The diagram below is not to scale. I'm trying to add a lens (or lenses) behind the one shown in this camera so that I can focus the image on a film plane of 15mm, rather than the current 120mm (Y). The focal length (X) needs to be at or greater than the current 60mm. What would the specifications be of a lens to accomplish this? Is it possible? Thank you in advance for any help you can provide!