The PK-3 Auto Extension Tube allows a lens to focus closer than its normal set minimum focusing distance. The PK-13 provides 27.5mm of extension. The rings can be used alone or in combination. It is compatible with older Nikon SLR bodies and lenses with a prong for meter coupling longer than 50mm, or with a reversed 50mm lens usinig a reverse adapter.
Nikon Auto Extension Rings PK and PN fit between the camera body and lens either individually or in combination. The extension rings have no optics. The PK and PN rings are used in manual focus mode and are considered non-CPU lens attachments.
Provides perfect coupling and retains both AI aperture and meter coupling. Does not support AF operation.