Oldies But Goodies:
Rejuvenating an Ultra-Micro-Nikkor lens
by Bjørn Rørslett 

High quality optics of bygone days still can produce stunning images. If modern cameras can be tricked into metering with them, that is. Read on to learn more.

Ever now and then I come across remarkable or interesting items. My Ultra-Micro-Nikkor lenses belong to this category. They were designed for industrial applications, for example in silicon wafer production. Optimised for narrow spectral ranges and fixed magnifications, the Ultra-Micro-Nikkors were top performers of their period and many of them perform close to the theoretical possible limits set by diffraction.

Why would anybody be foolish enough to use such old rarities, in a world bursting with all the latest optical innovations? Well, for my close-up photography these old lenses have certain desirable features all of their own. They can deliver outstandingly sharp images at wider apertures than any conventional Micro-Nikkor lens, thus throwing the background entirely out of focus. The non-focused background takes on a exceedingly soft, veiled and nearly shimmering quality, utterly unlike that of modern, highly corrected lenses. Because of their quite short focal lengths in conjunction with high speed, it often is possible for me to do hand-held close-up photography, something I normally cannot do.

However, even when I manage to coax such odd lenses into being mounted on my Nikons, using a plethora of lens adapters, metering remains a big issue. Athough my D1-series cameras will meter with such contraptions, only centre-weighted and spot metering modes are available. Centre-weighted metering is frequently very inaccurate with these lenses and spot metering often impractical, so getting matrix metering available is a big benefit. Of course, for a D100 user the question simply is to get metering at all with manual lenses. Enter the matrix chips from modern AF Nikkors. Thanks to the easiness by which modern consumer plastic zoom lenses self-destruct, and the fact that the people of my Nikon repair facility are really nice guys, I'm ensured of a plentiful supply of all those neat chips. The Nikon guys even provide free metal lens mounts on their most joyous days. Nice of them and good on me.

This article describes the project of converting an Ultra-Micro-Nikkor 55 mm f/2 lens, which I purchased very cheap from a German second-hand store many years ago. The 55 mm lens does not fully illuminate a 24 x 36 mm frame, but will cover the smaller digital frame of my D1-series Nikons. It has the advantage of not requiring to be reversed, unlike my 28 mm f/1.8 Ultra-Micro-Nikkor. With a working magnification around 1:3 it is perfect for flower close-ups. I initially opted for chip-modifying a CRT-Nikkor 55 mm f/1.2 (Oscilloscope lens), but the extremely large rear element of that lens and its Leica-thread mount made it impossible to fit a chip to it. So, I soldiered on with the 55 mm f/2 Ultra-Micro-Nikkor instead.

All the Bits and Pieces Needed for Conversion of the Ultra-Micro-Nikkor 55 mm lens
© Bjørn Rørslett/NN

Modifying an Ultra-Micro-Nikkor 55 mm f/2 lens to give it full matrix metering capability

The bits and pieces needed for conversion are as follows,

rubber sheathing (from the focusing collar of a wrecked AF Nikkor lens), CPU print (from a crashed AF 28-80 Nikkor) attached to a metal "F" lens mount (from a damaged AF 35-70 Nikkor), and a spare Leica 39 mm thread mount (from my odds-and-ends bin).The 4-fingered sliding contact is used for setting the "wide-open" aperture to any convenient value. The chip and print is a "D" type, however, as the increased print size was impractical in the context of the project, I simply cut away the "D" segment, after having tested that the chip continued to relay the aperture data to the camera.

And of course, there is the Ultra-Micro-Nikkor lens itself. In case you didn't know, it has an old-fashioned Leica mount.

(defect Nikkors were scavenged from the scrap heap of my Nikon repair facility so came absolutely free)


Lens Mount is Attached and the CPU Print Provisionally Laid Out

As depicted above, the Leica and Nikon lens mounts have been unified so as to allow the Ultra-Micro lens to be fitted. I just glued the mounts together using epoxy glue. The lens is screwed home and secured with a small set screw run through the rear bayonet. The contact board chafes into the Leica mount so a slight trimming is needed. A small metal file judiciously applied to the threads does the trick.

The CPU print has been provisionally laid out on the outside of the lens barrel. There simply is no way a print can be tucked away inside this particular lens. Putting the print on the outside makes it vulnerable, hence additional protective measures are needed (see later). I also locked the nominal aperture permanently (at f/3.5 as it were), this is just a value and doesn't mean anything as long as stop-down metering is employed. The camera merely displays the f-number reported to it by the CPU chip, and sets exposure according to the light levels recorded by its meter. Only if external light meters are consulted this discrepancy emerges, but if you prefer hand-held meters you are unlikely to embark on a matrix chip upgrade anyway).

(In answer to why f/3.5 was chosen: well, this combination of aperture and zoom lens setting from the print chip results in a unique EXIF identifier, so I , or rather my software, can tell the Ultra 55 has been used. Just for my statistics department, no real importance can be attached to this figure, but still fun)


The Finalized Lens

Here is the end result of the conversion. The original inconvenient 40.5 mm filter size has been expanded to 52 mm by a set of step-up rings. This allows for attaching filters and standard Nikon lens caps.

The rubber collar is the final touch, combining protection of the delicate chip circuitry with a better grip for mounting and detaching the lens.

(Mk.II shown here, slightly better fitting rubber collar)

The Ultra-Micro-Nikkor lens obviously was not designed for general photography. The need to have the SLR mirror clearing the rear end of the lens entails far too much lens extension as well, so lens performance is reduced even further. It reportedly is optimised for 1:4 magnification. Notwithstanding these potential issues, the lens projects images with biting sharpness at nearly all aperture settings. Just see for yourself (below).

Tyger, Tyger

Tyger, tyger, burning bright

in the forests of the night,

what immortal hand or eye

could frame thy fearful symmetry?

William Blake (1757-1827)

Photography © Bjørn Rørslett/NN 2002

Nikon D1X with Ultra-Micro-Nikkor 55 mm f/2 lens, shot at f/2.8

The literal 'bite' and crispness of the image rendition really set the Ultra-Micro-Nikkor apart from other lenses. Who cares about lens age when such results can be attained?

Oldies But Goodies: Rejuvenating an Ultra-Micro-Nikkor lens  

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Last Update 18 December, 2002