CPU installation, lens correction profile and tests.

In Part I I looked at the early history of zoom lenses on 35mm film cameras and at the Nikon Zoom 43-86mm f/3.5 optic, noting how the poor reputation for performance of the Mark I design had affected resale values of the improved Mark II version, which we are looking at here.

In this posting I address the installation of a CPU, examine the need for a lens correction profile to fix this optic’s barrel distortion and chromatic aberration, and provide some test images.

CPU installation permits the recording of EXIF data and automatic invocation of the appropriate lens correction profile when images are imported to Lightroom.

First the lens mount has to be removed, 5 screws. This will disclose shims both above and below the aperture ring. Be careful not to lose these and note how many are above and below the aperture ring.

Alloy will have to be removed in the area denoted.

Bayonet mount removed for grinding. Note the relatively fragile claw which mates with the aperture
follower deep in the lens’s barrel. Replace this mount incorrectly and you will lose aperture control.

For this lens, installing a CPU is difficult as a fair amount of alloy has to be removed from the rear of the lens mount to ensure the CPU does not protrude too far and damage the camera’s contacts in the lens throat. There is no easy way to access the area to be machined and while, once removed, the mount can be further dismantled I did not have the tools to do this. If you are not comfortable using hand machine tools you should delegate the work, as it’s not that difficult to mess things up here.

Shims disclosed when the bayonet mount is removed.

Dremel to the rescue. I found a Dremel tool, #7144 in 1/8″ shank at Home Depot for $8. This grinding tool has a very fine pointed diamond encrusted cutting surface and is just what the doctor ordered for grinding away the alloy on the rear of the lens mount to accommodate the CPU.

With the lens mount removed – 5 screws – and securely clamped in a vise, the Dremel 7144 tool goes to work.
Note the ear protectors to avoid loss of hearing. Blue masking tape denotes machining limits.

The correct positioning of the CPU is addressed here and is marked beforehand on the mount. The blue masking tape denotes the machining limits. A super smooth surface is not essential as the J&B Weld two part epoxy used to glue the CPU in place will fill in any irregularities. What you do want on a test fitting is a CPU whose electrical contacts are concentric with the lens mount and do not protrude above the extremity of the bayonet mount.

After the requisite 24 hour period to allow the epoxy to cure, excess glue was carefully removed with a sharp knife and miniature Nicholson file and abraded areas touched up with black matte modeler’s paint.

Be sure to align the fragile shims with the screw holes.
Unusually for a Nikkor, the five screws are equally spaced.
There are six holes in the shims, only five accept screws.

The CPU is installed. About 2 hours of work. If you get any glue on the sprung gold contact pins, the CPU is toast.

The CPU is programmed in the usual way as explained here, conferring maximum and minimum apertures, minimum focal length (I used 42mm as 43mm is not available in the CPU) and transferring aperture control from the camera body to the lens to avoid non-linearity issues as explained in that link.

EXIF data correctly reported in Lightroom
after CPU installation.

Lens profile:

Well, this is a surprise. I found that chromatic aberrations and barrel distortion in this lens to be so low that even without a lens profile results are fine.

However, I developed a lens correction profile in the usual way and this is automatically invoked in Lightroom if you install a CPU. The CPU’s program data tell LR which lens correction profile to use, something which will be done automatically if your image import dialog checked the lens correction profile when you created it. You can download the profile here. The profile file contains corrections at f/3.5, f/8 and f/16. The closest to the aperture used will be invoked automatically.

Here’s the Develop dialog from LR:

The profile invoked in LR.

While developed using a Nikon D3x, this profile will work fine with any Nikon digital camera, FF or APS-C.

Performance:

I was very pleasantly surprised by the performance of this optic, finding excellent center and extreme edge definition at 43mm and 86mm fully open and even better at f/8 where the lens peaks. Thereafter, it’s just fine all the way down to f/22. It mystifies me what all those years of opprobrium and trash talk directed at this inexpensive lens are all about.

The images below were reproduced without invoking my lens correction profile (see above) and mild chromatic aberration (color fringing) is visible. This completely disappears when the lens correction profile is used.

Test scene, Nikon D3x, 43mm full aperture.

Center definition at f/3.5. 40x enlargement.

Extreme edge definition at f/3.5. 40x enlargement.

Extreme edge definition at f/8. 40x enlargement.

Compare these test images with those from the 50mm f/2 HC Nikkor, one of the best lenses ever made. Impressive, huh? Also note the gentle rendering of out-of-focus areas.

Conclusion:. If you want a mid-range, constant aperture Nikkor push-pull zoom for very little money, snap up the Type II version of the 43-86mm f/3.5. The results are excellent and the ergonomics, fit and finish are unequalled in any zoom lens I have used.

Gear used for the above, including a $6 Amazon Basics UV
filter and a Nikon HR-1 folding rubber lens hood.

On an APS-C format Nikon, where the extreme edges are not used, this makes for a fine all purpose 65-130mm, high definition optic. In fact I did the CPU programming on my D2x, which is APS-C, sporting a 1.5x magnification compared to the full frame D3x.

The story here is similar to the one for the 500mm Reflex Mirror which, were all those purported ‘experts’ to be believed, is not worthy of serving as an ashtray.

Not totally awful.

The early history of zoom lenses on 35mm film cameras is long and not distinguished.

It starts in 1959 with the 36-82mm f/2.8 Zoomar which mounted on the contemporary Voigtländer Bessamatic SLR. The Bessamatic used a leaf shutter inside the lens mount, a fact which made it difficult to make really wide lenses for it, but kudos to the company for retaining American Zoomar to design a zoom lens, and one with a fixed, large aperture at that.

Bessamatic with 36-82mm f/2.8 Zoomar mounted. No strap lugs on the body ….

This monster lens was an ugly duckling with styling nothing like the nicely finished factory lens range (35mm all the way through 350mm) and performance was so-so, but you could claim to be the only one on the block with this ugly duckling. Plus, the optic came with this comical depth-of-field calculator so that you could be sure of getting it right despite the multiple aberrations:

Included with every Zoomar, this DOF calculator. Reminiscent of Dr. Strangelove’s circular slide rule.

Nikon was a far better lens designer than American Zoomar, so when they first marketed their 43-86mm f/3.5 Nikkor Zoom in February, 1963 it was elegantly executed and matched, as a whole, the rest of the burgeoning Nikkor lens range:

Mark I of the 43-86mm Nikkor.

Nikon’s elegant solution to the depth-of-field riddle.

And the elegant solution to depth-of-field determination with those lovely curving, colored lines, was a first. A tad different from the Zoomar’s calculator!

Arguably one of the most beautifully executed of all Nikkors its performance was, by general agreement, the worst of any lens Nikon ever sold! Despite that, over 150,000 made it out the door at Kogaku, Tokyo. The lens was compactly sized and beautifully made, not to mention revolutionary, building on Voigtländer’s pioneering lead with something far more useable. This design comprised 9 elements in 7 groups and as Nikon’s site attests, the manufacturer was rightly proud of its achievement. The irony of the lens’s poor optical performance is that 99+% of images are now displayed on small computer or cellphone screens, for which purpose it’s perfectly adequate.

Nikon had another go at the design, releasing Mark II in November 1975, now with 11 elements in 8 groups, the description of the lens was moved from inside the filter ring to around the outside barrel, making identification easy. This was a much better optical formula and the beauty of the marketplace is that the curse of the earlier design similarly affected the market price of used Mark II lenses, meaning all are dirt cheap. Mine ran me $69 shipped, in ‘as new’ condition. Many of these have been really beaten up and I simply cannot see saving $30 on a beater when your pride and joy in a mint example can be had for little more. It probably makes sense to use a lens hood for protection as well as flare control, given how prominent the front element is, and the standard Nikon 50mm collapsible rubber hood HR-2 can be found new for under $20. Amazon lists an ‘Amazon Basics’ 52mm UV filter for further protection for under $6. I bought both.

An even greater number of the Mark II variant was manufactured with the last versions – mine – coming Ai equipped from the factory. The cut-outs in the aperture ring’s coupling claw for old Nikon Photomic metered prisms and cameras like the Nikkormats are there to throw as much light as possible on the smaller duplicate rear aperture scale which is read through the finder via a reflecting mirror in later bodies like the FM and FE. Nikon called this ADR or Aperture Direct Readout, a clunky solution to seeing the aperture in the viewfinder. It works …. in good light. As usual I will be discarding the claw after installing a CPU, which will allow the recording of EXIF data on digital bodies.

My ‘as new’ condition 43-86mm Zoom Nikkor on the Nikon FE film body.

Mounted on the small FE body the fine ergonomics of the body are nicely complemented by this compact and beautifully made zoom lens. The construction quality of the lens is exceptional as regards fit and finish, no wobbles, no rattles and the optic feels like one solid piece of glass and metal. Those are real, paint filled engravings you see, not screen printed garbage. Gorgeous.

I discuss lens correction profiles and CPU installation in Part II, along with test images.

An ancient lens made even better.

I wrote about the excellent standard 50mm Nikkor lens for film SLRs years ago here. That lens first saw the light of day on the Nikon F in 1964 and Nikon made hundreds of thousands of them, a fair reflection of this optic’s outstanding performance, small size and toughness.

The last version made in the classic scalloped, metal focus collar style came to market in late 1972 and was optically identical with the happy addition of multicoating for better performance when bright light sources were in the image.

I had given away my 50mm f/2 H to a friend when the 50mm f/1.4 came along, that lens’s greater bulk balancing far better on the large DSLR bodies.

The f/2 continued to be made in later mounts with rubberized focus collars through 1979, though the optical formula remained unchanged.

When I recently added a film era Nikon FE to my little hardware collection I found I was hankering for the original 50mm f/2 as its small size would perfectly complement the comp0act FE body, and managed to snap up a mint HC, factory converted to Ai no less, for all of $70. Yes, I could have bought a beater for half that but why would you want to save $35 and suffer mental anguish every time you looked at the scarred black anodized finish which is as ugly as it gets? Here it is, mounted on the FE, the satin black front ring denoting multicoating, replacing the silver one on single coated lenses:

The factory Ai ring adds a second row of aperture digits which is read by the small mirrored assembly in the base of the camera’s prism and reflected into the viewfinder. Nice – you can see shutter speed and aperture through the eyepiece.

Nikon has a remarkably honest assessment of this optic’s performance on its site here and their statement about performance accords exactly with my experience:

The very minor vignetting at full aperture along with mild barrel distortion are both easily corrected using my lens correction profile in PS or LR and, if you install a CPU in the lens then that profile can be invoked automatically when you load your images into LR. CPU installation is very easy as no machining is required and the ‘Dandelion’ CPU can be found from commie vendors on eBay – just search for ‘Dandelion chip’, all of $20. My link in this paragraph includes my installation (Part I) and programming instructions (Part II) and you will not find any better. I have installed around thirty of these and they continue working fine after many years.

Here’s how the lens’s data appear – automatically – in Lightroom, for images made with a digital camera:

I find lens EXIF data extremely useful in the image catalog for, when searching for some long forgotten image, I tend to remember the lens used more than anything else. In the example above the image was snapped on the D2x with its 1.5x crop factor.

Here’s the data on the lens correction profile – while the image was snapped on the D2x, the profile was created on the D700 and that’s what I put in the file name for the profile:

The 50mm f/2 Nikkor is recommended without reservation and can be found in any condition you like for very little. You get Leica Summicron performance for 5% of the outlay and if you drop it, heck, buy another. Plus, it’s better made than the Leica lens.

The f/1.4 is larger and heavier. The epoxy is still drying on the f/2’s CPU!

An old friend. Nikon D2x, 50mm Nikkor H at f/2.

And while I’m at it, if you want a truly unbreakable DSLR in APS-C format for well under $500, you can do a lot worse than the Nikon D2x, which is backward compatible with almost every Nikkor ever made. At 12mp it’s no pixel monster but that’s fine for up to 40″ x 60″ prints and, of course, you make those all the time, right?

Field tests:

You can judge the extent to which the lens vignettes from the sky in these two images:

Center and edge definition – note the EXIF data from Lightroom in these screenshots, conferred by the newly installed CPU:

Center definition at f/2, 48″ x 72″ print. Note the gentle rendering out-of-focus areas.

Center definition at f/4, 48″ x 72″ print.

Extreme edge definition at f/4.

Like I said, Leica Summicron optics at a fraction of the price. Comparing performance in the extreme corners with that of the 50mm f/1.4 Nikkor of like vintage, the f/2 optic shows no noticeable flare compared with the f/1.4 (probably thanks to the multi-coating in the f/2) and is one stop sharper, meaning that the f/2 is as good at f/2 as the f/1.4 is at f/2.8. That said, either lens will make fine large prints at full aperture, sharp enough to please all but the meanest pixel peepers.