Micro-NIKKOR-P Auto 55mm --> Ai conversion

Started Aug 14, 2017 | Discussions thread
Just Tim 3 Contributing Member • Posts: 880
Re: Micro-NIKKOR-P Auto 55mm --> Ai conversion

Captain Hook wrote:

Mark9473 wrote:

That lens looks exquisite! It's remarkable how different it looks from the 55/2.8 AIS version that I'm using. Yours is a piece of art.


Yes, I found it @ local second hand photographic website, checked if it really was this specific model as described by Bjørn Rørslett:


55 mm f/3.5 Micro-Nikkor Auto (Compensating Aperture)

5(up close)

The modified Micro-Nikkor from the mid '60 had much flatter image field than the first version of 1961, and gave close-ups with tremendous sharpness. Despite its single-layer coating, the deeply recessed front element ensured flare problems were minimised. This lens had an outstanding feature directed at the non-TTL light meters of its era, viz. an aperture that changed f/numbers by itself as the lens was focused closer. This meant the photographer could measure exposure the usual way and let the lens take care of the adjustment needed by the close-focus extension. Really neat if you didn't use TTL (I did TTL, however, with my Nikon F Photomic of these halcyon days, and the aperture re-re-adjustment was cumbersome indeed - I ended up doing stopped-down metering with it). The 55 mm Micro was optimised for close-ups with peak performance at 1:10 magnification, and the image quality suffered when it was used for landscape shots. For close-up work, peak performance was between f/5.6 and f/8. The near symmetrical design ensured that it performed well when reversed onto a bellows or extension tubes. I have used it this way successfully for shooting macro images on 6x9 cm and 4x5" formats.
Some confusion exists as to which Micro-Nikkor is the one with adjusting aperture. Partly this is due to the term "Micro-Nikkor P" used in Nikon literature, whilst the lens itself only is engraved "Auto". At least my sample is. Since there is an immediate successor without the compensating feature, but "P" designation, identifying this model is not easy. However, a lens with chrome barrel, magnification factors printed in light blue, and hill-and-dale focusing and aperture collars likely is the real thing.

And made a good deal with the seller, for this lens.

The seller didn't think a proper Ai conversion was possible/feasible, but I proved him wrong.

There are two different versions here, not to be confused. The one with the metal, (hill and valley), focus ring is the compensating version discussed in your italics above. The one with the rubber ring is the later non-compensating version. Although the same optical formula it does not have the compensating aperture and it is corrected more for general use. The compensating version was corrected for close-up and really optimised for 300mm or there about, a little "soft" at infinity. Yours is the later one corrected for more general use. An excellent lens, very sharp with a very flat field. If you look at my image in the post above the compensating version is the one on the right with the PC, or P, version in the middle.

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