DF: movable rail or bar used as the reference axis for spectacles during measurement, which is aligned perpendicularly to the optical axis of the focimeter and parallel to the 0° – 180° axis direction
DF: movable rail or bar used as the reference axis for spectacles during measurement, which is aligned perpendicularly to the optical axis of the focimeter and parallel to the 0° – 180° axis direction
DF: movable rail or bar used as the reference axis for spectacles during measurement, which is aligned perpendicularly to the optical axis of the focimeter and parallel to the 0° – 180° axis direction