The NPC Proback II uses a free-floating fiber optic lens to transfer the image from the camera film plane to the Polaroid film plane without any degradation of the image. Because the fiber optic bundle is in complete contact with the Polaroid film, the image is transferred with absolute sharpness and fidelity.
There is no light loss and no color shift. This back lets you make two independent images on each sheet of Polaroid film simply by pulling the white film tab to a predetermined position before taking the second picture.
Instantly, you can do a side-by-side comparison to evaluate varying composition, subtle lighting changes, or results produced by lenses of different focal lengths.