There are hack-job conversions that result in functional lenses but are irreversible and there conversions that use genuine Nikon factory conversion kits that allow you to undo your conversion without damage to the lens. Also a conversion with a genuine Nikon factory conversion kit results in a lens that is both functional and that has lost nothing of its collector value (as owners used the factory service to upgrade their lens). Also, the conversion with a genuine kit is a dead easy job.... just loosen some screw and swap out a ring, as well as the rabbit ears (see here )