Is this a flat field lens?
When I was about 14 years of age my dad bought a new slide projector, that is some 40 odd years ago, it was a Rollei made by Franke and Heidecke, the projector is still functional and still in the family! F & H is about the last company today that stll makes high quality projectors. As requested by one forum member , this forum is more than appropriate !