This Rodenstock Correction Plate is for use with the Rodenstock 28mm HR Digaron S and Apo Sironar Digital HR Lenses only. The Correction Plate is needed only when working with film. This is because the cover glass over the sensor on digital backs is part of the optical formula. If you don't use the correction plate when shooting film, you will be out of focus by 1/3 the thickness of the correction plate.
Note: This Correction Plate is ONLY used with film, and with the lenses listed