Could you be referring to Makinon lenses? They're an off-brand, but not expensive, and many were sold through Black's Cameras in Canada. I have a 500 f8 mirror lens that gives me acceptable images (better now that I use a slip-on lens hood made from some black card and a rubber band. I leave it on the lens and slide it forward a couple of inches before taking a picture. Very noticeable improvement in contrast.) and didn't cost much.
Pat White
