Nikon Pn-11 Ai Auto Ext Tube 52.5mm
Excellent condition !!!!
The Nikon PN-11 has been my regular extension tube for my closeup photography. It is a 52.5mm manual focus extension tube with an auto AI, originally designed for the Nikon manual focus Micro-Nikkor 105mm f/4 AI or 105mm f/2.8 AIS to achieve a magnification of 1:1 ratio. However, the PN-11 is not restricted to be used with these two lenses; it is nothing more than being an extension tube allowing these two lenses to focus loser. I use it primarily with my autofocus Nikon 180mm f/2.8 ED-IF for closeup photography (or, rather, to get this lens focus closer). What makes the PN-11 so unique and special is its tripod collar that allows changing format from vertical to horizontal a pleasure to use. I am quite pleased with the results I get using my 180mm lens with the Nikon PN-11 tube. Since it is merely an extension tube, image quality of a lens is fully retained.
With my Nikon 180mm f/2.8 ED-IF AF, the PN-11 provides a little over 1/4 magnification (1:3.43) with minimum working distance (front lens-to-subject distance) of 21 inches and maximum distance of 30 inches and a light lost of about 1/2 stop. Losing a half stop of light is not that bad, especially if I start with an already bright lens to work with. Photographing flowers or small creatures (like medium-sized butterflies), the working distance with this magnification is usually enough. I often combine this tube with Nikon PK-series (namely, PK-11A, PK-12 and PK-13) to obtain a higher magnification. With all four tubes combined (yielding an effective extension of 102mm), magnification is 1:1.76 ratio, a little over 1/2 life size.
Since this PN-11 is a manual focus extension tube, an autofocus lens will lose its AF capability. But that doesn't matter since I always focus manually anyway.
http://www.epinions.com/review/Nikon_Pn_11_Ai_Auto_Ext_Tube_52_5mm/content_80844721796?sb=1
