I have a set of the same lenses ie: 150 210 and 300 that I took off a vertical process camera last year some time. I seem to remember that the camera was a DS America process camera. Try it out without the spacers and let us know the results. I have a 210 g-claron and a 305 g-claron and they don't have spacers in them. They are in a Copal #1. They( the g-clarons) are as sharp as any lens I have owned.\