True macro lenses, designed for the high magnication rates found in photomacrography, are professional tools of high optical performance and, not unexpectedly, with a commensurate steep asking price. The needs in the field of photomacrography don't follow the whims and hyped trends so frequently encountered in other branches of photography. For demanding macro work, the old and trustworthy lenses were, and still are, the optimal tools to get the job done. What a pity the manufacturers of these optical gems don't allow such superb optics to be put to advantage with their newest digital cameras. No fancy colour or matrix metering is possible, and some cameras won't even meter with such lenses. Or is this the end of story? Read on to learn more.

After I had a number of my manual Nikkors chip-modified by Rolland Elliott or myself to make them work on F5 and D1/D1X/D1H, an idea dawned on me. Wouldn't a chip inside an extension tube solve the remaining issues for my macro lenses? And could I, finally, obtain really precise metering also with the macro lenses or bellows attachments? My D1-series cameras would meter even with such contraptions attached to them, but with highly variable and unreliable results, and using D-TTL flash only exacerbated the situation. Of course, for a D100 user the question simply is to get metering at all with manual lenses. So improvements could and should be sought.

Obviously no linkage to the lens aperture control should be active, because stop-down metering has to be used for the candidate lenses for proper macro work, be they dedicated macro lenses or just ordinary lenses used in a reversed position. If the extension tube could convey the aperture on the master lens, this would literally screw up all metering, because stopped-down metering on any lens with an automatic aperture control is disabled on all new Nikons.

Autofocus is a big practical joke as far as close-up photography is concerned, so losing this feature is of no concern for photomacrography. Stopped-down metering may seem old-fashioned, but again, in the high-magnification field you have to light the specimens with intense light if you wish to see anything except total blackness in your viewfinder. So, with a photomacrographic setup work progresses slowly by its very nature and lacking an automatic aperture is actually a bonus due to one less item causing vibration.

One of my sharpest lenses is the Micro-Nikkor Auto 55 mm f/3.5, from 1967. This lens has a peculiar compensating aperture mechanism, which means the aperture changes its effective setting when the lens is focused. The idea was to give the effective aperture corresponding to the magnification rate of the lens. This works like a charm of course when a separate hand-held meter is used for metering, and the lens set to the indicated aperture value. However, coupled to a TTL system metering with the lens wide open, the wrong exposure would result, because the lens would inform the meter of its nominal setting while in fact a compensated setting was used. The circuitry found inside today's Micro-Nikkors solves this problem and communicate the effective aperture to the camera, so no issue exists (with the possible exception on the user's behalf, because people fail to understand why a setting of f/2.8 at infinity is displayed as f/5 at 1:1 with AF Micro-Nikkor 105 lens. Instead of reading the instruction sheets accompanying their lens, they post silly questions on the Internet).

Anyhow, I had the old compensating-type 55 mm Micro-Nikkor, which could not be used on any of my digital cameras even if AI-modified, and the dedicated "M" extension tube for it. The M ring, superceded by M2 and later the PK13 extension tube, then underwent cybernetic surgery by adding the chip print from a pedestrian 28-80 Nikkor, and the metal lens mount from a 35-70 AF Nikkor (both Nikkors were scavenged from the scrap heap of my Nikon repair facility so came free. Most repair shops should be able to supply the needed parts). Which chip used isn't important, but getting the chip grafted onto the ring is paramount. Any extension ring could be used as long as there is space to encompass the chip print board. If you replace the ring's lens mount with a new already outfitted for mounting the contact points (see below), the task is eased considerably.

Well, that's about it. With the CPU in the modified M ring, communication to the camera can be established and the camera is in no position to understand it has been deceived. Put the aperture on your lens to any suitable setting, and the camera's meter will track the alterations in light levels. Switch to matrix, spot, or centre-weighted metering to your heart's pleasure. Even the latest development, DTTL flash, will work, but obviously not in "D" mode because no distance data can be relayed from the extension ring, even when a "D"-type chip is placed inside it.

I've shot a lot with an assortment of lenses using my CPU-fortified extension rings and can testify the exposures now are vastly improved compared to the previous use of non-modified extension tubes. Sometimes I do ponder the vacillating trend of evolution, since my F2 AS (1978) still is able to obtain highly accurate TTL metering with any lens or optical device mounted on it. But, of course, even the mighty F2 fails to do D-TTL flash or colour matrix metering. So, given the modern cameras are to be used, they actually need having all the chip-mediated assistance they can get if you want spot-on exposures.

After the initial success with the M ring, I have modified several other extension tubes and reversal rings. Besides the M ring, other alternatives would be the M2 or E2 rings, both of which provide sufficient interior space to hide away the CPU print. The odd item from the old-fashioned K-ring set may be pressed into service for this purpose as well. Some of prints need to be folded up once or twice to fit into the tubes. For the ultra-thin K1 ring, the print has to be hung outside of the ring because there is no physical space for any of the print, except for the electric contact points, inside the K1 itself. I have to make the K1 setup more suitable for field use by encasing the print in laminated plastics to make it water-tight. A project for the next upcoming period of low activity, whenever (or if) this happens.

Another use of the chips is for some of my highly exotic lenses, such as the super-speed Rodenstock Heligons. The latest addition, XR-Heligon 75 mm f/1.1, has just got a chip permantly grafted onto it. For the 50 mm f/0.75 lens, I have used a chip-equipped narrow extension ring, but depending on the practical shooting experience from the 75 mm lens, I might implant a chip on the shorter lens, too.

All modern Nikon bodies have sculptured outlines which conflict with items such as a bellows. Hence a narrow extension ring is needed for correct spacing anyway, otherwise the camera won't mount on the bellows. Put the modified M ring as a spacer and suddenly all modern camera features such as colour and matrix metering are available to your digital close-up and photomacrographic system. Neat, isn't it?

For Nikon D1-series models, any D, non-D, or G chip can be used, while D100 or similarly designed cameras need the G-type prints for the modified extension tubes. Alternatively, a stop-down tab can be added to the extension ring (see picture above). Whichever chip is used, you have to pay attention so as to have it set to its maximum aperture value (G lenses default to have apertures dialled on the camera and this overrides any custom setting for aperture control mode). This is needed every time the ring is attached to the camera and the previously employed aperture doesn't coincide with the value reported by the modified tube. Otherwise the camera, which you have tricked into thinking a real CPU-equipped lens was mounted, may strike back and play havoc with the exposure. If you use D1-series cameras programmed to set apertures directly on the lenses, my preferred setup, non-G chips will work perfectly and you won't be troubled with the caveat described earlier.