A couple of thoughts with respect to copying flat originals. There is a reference to distortion. This common problem is caused by lenses not being symmetrical (front elements the same as the rear elements). There are lenses designed for producing color separations. They are known as Apocromats. They are corrected for three colors instead of two. If there is any way to use them, they can probably be found second hand at bargain prices. They were once very expensive. One name to look for would Artar produced by Goertz American Optics. The images these lenses produce from color originals are very much better than those produced with regular lenses. Malcolm Smith.