The Nikon PK-13 Auto Extension Ring is a 27.5mm Auto Extension Tube that enables a lens to focus closer than its normal set minimum focusing distance. The PK-13 Extension Tube can be used with any Nikon SLR lenses longer than 50mm, or with a reversed 50mm lens (using a reverse adapter). An AI NIKKOR will retain automatic diaphragm and meter coupling functions, letting you compose, focus and meter at a wide-open aperture, making them excellent devices for macro photography. Use one or more extension rings for further creative capabilities, placed between the lens and camera body. The tubes can also be used for manual exposure control.
*Note: Exposure meter does not work with D90, D60, D3000, D5000. G-Type lenses cannot be used. Supports AF-S lenses in Manual mode only.