*For the best results, C RX lenses were to be used only on Bolex H16 Reflex cameras. It's true vice versa; those cameras are supposed to take only C RX mount lenses. The C RX lenses were specifically designed to compensate the issue raised by the beam-splitter prism (for the reflex viewfinder). Some people use the lenses any way and achieve pretty good results due to the quality of the lens, but they are not the best possible results. Standard C mount can be used on nonreflex Bolex cameras.