Compensating MIcro Nikkor 55mm f/3.5 revisited

[Bernard Delley]

Interesting, I had not noticed before that different measures were given for the 5/4 design of the Micro Nikkor.  I got the latest series of compensating 55mm and see no significant difference against a late AI version.  I now wonder If there was an optical design change between the compensating sub - versions. What serial number is that lens with different lens diameter?  Bey Eyeballing the comp versus the AI a change in lens diameter was not obvious.
The Nikon 1001 tale 26  alludes to a change between the very early "preset"   5/3 ? version  and the later 5/4 . It mentions that the optical design of the
55mm f/3.5 'without change of the "basic" design since 1963 till the end of the f/3.5 ' .  -- Of course there is a weasel word : "basic"

[Bjørn Rørslett]

This might be stated before but bears repetition: Nikon tend to carry out tweaking and polishing the design of their lenses throughout the product life. Usually without making the alterations public. Changes could be modification of coatings or sometimes using a different kind of glass, or adjusting the thickness and spacing of the elements.

[Erik Lund]

Our friend Roland keeps a very useful site for questions like this:

http://www.photosynthesis.co.nz/nikon/specs.html#55Micro

Here you can see the major 'types'

[Bernard Delley]

So there are clear indications that the 5/4 design may have been tweaked, as Roland mentioned first, EriK measured diameter and Asle reminded us that different drawings are up at the mir site.

Roland's  page with serial numbers http://www.photosynthesis.co.nz/nikon/serialno.html#55Micro  is indicating that there were 4 sub-series of compensating versions with small obvious differences between Mar 1963  and 1968?  The open question is if a tweak to the optices was done between those 4 sub-series. I got a sample from the latest sub-series of compensationg 1968? and the latest AI sub series  Oct 1979. Other than the change in coating I do not see a significant change between these concerning optimization for close range. The aberrations at 1:1 show the same lateral color aberration as the dominant aberration. I try to attach small 100% crops from the lower edge center. The image of the blue patch is shifted up towards the center of the entire image  and the red patch is shifted down away from the center. Remember the full size of the 'Retina' screen pixel is 115micro meter. a1 compensating 1:1 a2 non-comp AI  1:1 and   a3 55mm reverse on bellows 4x  show just a little longitudinal color aberration putting the red slightly out of focus.    My conclusion here its no funny property of the target, there is no significant difference in close-up optimization between my two samples.  Small differences in appearance are due to the difficulty in obtaining precise focus using the PB6 bar as macro rail.

So I see the question now as: can we find evidence that an optical tweak concerning close up optimization was done before the final sub-series of the compensating 55mm f/3.5

[Bjørn Rørslett]

First and foremost, these lenses were designed for film. So colour aberrations seen on a digital camera may or may not relate to the original scheme of optimisation. I think it's necessary to stress this basic fact one more time. A lot of the older lenses do exhibit chromatic issues *not* seen on film. A typical example is the fast 24/2 Nikkor.

Secondly, lateral chromatic aberration is easily dealt with in the digital domain. Any issue that is gone by a simple mouse click action is pretty academic and moot to me. What is more of interest is the axial (longitudinal) kind of colour artefacts. These are potentially much more objectionable.

Thirdly, you should repeat your observations using a better target. A LCD screen up close will show lateral issues simply by focusing a tiny bit differently. Shoot some wildlife objects and show us how these lenses behave then.

[Roland Vink]

It's worth noting the 4 sub-versions of the compensating 55/3.5 micro are largely cosmetic (change from chrome to black) or mechanical (change to aperture ring allowing AI kit 63 to be used). These changes say nothing about internal modifications (which are not visible to the casual observer) or whether any optical changes occurred.

My site groups lenses together with the same optical design (to the best of my knowledge). Lenses with different optics are separated by a thick dark grey line. Minor changes to an existing design are separated by a thin dark grey line. In this case I show a minor change between the compensating and non-compensating versions. This seems to be the logical place for it to occur and it is broadly supported by the documentation I have seen. But it is possible the change occurred at a different point, or there were several changes over the lifetime of the lens of which we know only two.

As for testing, if the earlier version is better at close range and the later version is better at distance, then tests at or near infinity may show differences in performance more clearly.

[Roland Vink]

Nikon were continuously tweaking their Micro-Nikkor designs. The earliest 5.5 cm f/3.5 had very steeply curved rear element, and if memory serves a 5/3 compared to the later 5/4 design, to name one example.

Maybe you are thinking of the 105/4 micro which has a 5/3 design. The 55/3.5 micro originated with the rangefinder 5cm 1:3.5 micro, which has a 5/4 xenotar (modified gaussian) design - with a steeply curved rear element. When the original F-mount design was being considered, the back focus of the 5cm lens was too short to clear the reflex mirror. The designers more or less scaled the original lens up by 10% to provide sufficient clearance, giving us the familiar 55mm 1:3.5 micro with xenotar 5/4 design and steeply curved rear element. The original 5.5cm preset lens had rather poor handling so was soon replaced by the compensating 55mm micro with automatic aperture, using the same optical system (http://www.nikkor.com/story/0025/).

[Bjørn Rørslett]

You might be right, Roland. I haven't taken my 5.5 cm Micro-Nikkor apart. However, it surely is quite different in every aspect from the later 55 mm models succeeding it. It goes to 1:1 directly and has the most awkward user interface ever. The overhang of the aperture ring is thick and extends so far to the rear that it is impossible to focus the lens to infinity on anything else than the original F (or perhaps F2. Haven't tried). Image quality is good up close, but the corners aren't good until the lens is taken down a few stops. The infinity performance is nothing to write home about, provided you can reach infinity at all that is. There are two sets of filter threads, one hidden deep into the front of the lens so can only be reached through a special funnel-shaped adapter that *should* accompany the lens but often has been split off and lost. The other set of threads is in the usual front position. The aperture is clock-stopped but operates without any linkage so has to be closed down manually.

[Bernard Delley]

Bjørn,

Oh, can you tell us the serial number please?

I wrote the stuff below some two days ago, but could not send it, because of poor internet on my trip.

I got this lens hoping for better close-up correction primarily in slide reproduction at 1:1 or 1:1.5 . My test would easily show it, if there was a significant change in close-up correction.  The lateral color is easily quantifiable with this test. The longitudinal color aberration is also seen and experienced dramatically while focusing, but harder to quantify. Sharpness could also be quantified. All these findings hint strongly that there is NO significant change in correction between the late compensating version I got and a much later AI.  I am convinced that two lenses could not look so equal in this test, if they were in fact quite different.
(when back from my travel I may show results for other lenses, if I feel there is interest. It seems, I mostly get dismissal)

For my use, the question is if there is an older 55mm f/3.5 that qualifies as the real thing for close-up as compared to the later 55mm f/3.5 versions. We have your statement and hints in this thread from Eric and Asle that there is a different optical tweak among the compensating 55mm. From my findings and Rolands table on serial numbers  it would have to be with serial number between 188128 and  268251.  My sample, is from the last compensation series # 269089 - 273083 . 

To comment on the points you raised. The film lenses were designed for no optical stack in front of the sensor.  Indeed the about 2mm of transparent material in front of the sensor is most likely considered in current lens designs.  (There are indications that Nikon is not evangelic about using the same thickness in all models)  For highly corrected, high aperture, ultra wide angle lenses this really matters for top performance.  My back of envelope calculation assuming 2mm crown glass, using Snell's law, indicates that aberrations introduced by it for macro stay well below 1 micro meter. This is much less aberration than seen in my test.

I fully agree that lateral color  per se is not that important as it is easily corrected in post. -- To some degree at least it does: I have tried it. One may declare that the AI 55mm f/3.5 is sufficiently good for slide reproduction: it resolves Kodochrome II grain to the edge at nominal f/8. With lateral color correction in PS even better.  However, I use lateral color aberrations as indicator of the correction status of the lens. A lens designed for film with better matched optimization for close-up should be expected to have less lateral color than the sample with less well matched optimization.  The ease of correction in postprocessing for lateral color and distortion may relax the requirements on lateral color a bit for modern lens designs.

To the third point. Anybody who cares to do a similar test on a glossy screen will easily verify that lateral color of that size is not a consequence of the target. It is also the same Snell's law calculation saying that the perhaps 2mm of class over the liquid crystal lead to a less than 1 micrometer effect due to the target.

[Bjørn Rørslett]

No experience with the glossy screens so  concede I might have been mistaken there. If your interests
are close-up it is understandable infinity testing is less important. In its heydays, the 55/3.5 was denoted 'macro-normal' and saw universal application also for landscapes and suchlike motifs. I used it myself in that manner and never was enamoured by anything beyond the first 1-2 m of shooting reach. The later 55/3.5 AI was smoother and better for intermediate to distant scenes. The 55/2.8 bettered that, but my enthusiasm for that lens quickly waned when I experiences all the troubles a sticky aperture would cause. Had the lens cleaned professionally twice but never could rely on it so threw it away.

My compensating Nikkor 55/3.5 has sustained a damage at the front that makes the first part of the serial number hard to read. Apparently the first 2 digits are 23 or 24. The damage must have occurred 45+ years ago so memory fails me as to what happened to it back then. The lens still works, though, and that's what matters to me.

[Roland Vink]

We have your statement and hints in this thread from Eric and Asle that there is a different optical tweak among the compensating 55mm. From my findings and Rolands table on serial numbers  it would have to be with serial number between 188128 and  268251.  My sample, is from the last compensation series # 269089 - 273083 .

That means your compensating lens is very late and has dual focus scales in feet and m. All the earlier lenses have one focus scale in feet only, or sometimes m only. This particular change is purely cosmetic and has no bearing on the optical system, which is likely unchanged. I have an early compensating model with chrome barrel and a later model with black barrel, also a non-compensating micro-Nikkor-P, K and AI models. I can't see any obvious differences in the size or shape of the front or rear elements, apart from improvements in coatings. Any differences are likely to be at sub-mm level or changes to glass materials, so would only be seen with careful measurement.

[Erik Lund]

........ We have your statement and hints in this thread from Eric and Asle that there is a different optical tweak among the compensating 55mm. ...

No, we are not talking about differences within the Compensating type series. They where cosmetically on the lens barrel as Roland clearly has stated.

[Bernard Delley]

Bjørn,

so you got a sample from the sub-series before my sample.  It is possible that there was a real tweak to the glass. Though Roland contends that the changes look only superficial. Alternatively, the poor performance at distance might come from a particularly poor infinity stop, similar to my AI 200mm f/4 which has impressive sharpness up to maybe  200m distance, but set at the infinity stop only gets sort of hyperfocal blur circles on stars.

I also used my AI 55mm f/3.5 as general lens predominantly for non-macro objects.  With digital landscape  interest for this lens is lost (clearly not as good as other options) but for more extreme macro of still objects it stands its own. Important application is now slide copying onto 36 mpix FX or 24 mpix DX - sometimes landscape images shot with that same lens.

If you already have one of these Apple computers with a screen called ''retina" (If you do not, you really might like the sharpness these can deliver :-) ) it would certainly be a piece of cake for you to a glossy screen test and get to know your comp Micro Nikkor from this side.

For everybody's entertainment I attach a few 100% crops from the left edge  at 1:1.5  the reduction needed for 35mm slide  to 24 mpix DX D7100.   (the center of these images look 'perfect')
First attachment is from the compensating 55mm at nominal f/5.6.  The lateral color pulls the tricolore apart and mostly puts red on top of blue resulting in a magenta patch.
Second, same again for the AI version. Same issue.  The red and blue show up at the 2pix wide black mark I put on the screen.
For comparison, same crop left for the youngest sibling the AFS 60mm f/2.8    (at  f/8 shown on camera and believed to be real).
Her the tricolore survives, albeit somehow compressed with wider black interstitial.  The lateral color goes  in the other direction as with the old Micro Nikkors: blue moves radially out and red moves radially in !
So whats on the right hand edge then for the 60mm lens? 4th attachment shows it. The  right side is  very similar to the old Micro Nikkor's on their left. It is also true vice-versa. The new AFS 60mm f/2.8 has about the same lateral color at 1:1.5 , but with opposite sign, as the old Micro Nikkor's .  It has  kind of an over-corrected lateral color aberration with its very complex new design. As discussed before, lateral color has lost a bit importance among modern design goals because of easy correction in post.  (This test also underlines that this lateral is not due to the test target)

So at 1:1.5  the new Micro Nikkor is not really much better than the 50 years old ancestor !

Well, a 1:1 its a different story. The lateral increases in the old 55mm but the AFS 60mm G is almost perfect: attachment 5.

[Bjørn Rørslett]

Not very likely I'll get a Mac with Retinsa display

[Erik Lund]

..., the poor performance at distance might come from a particularly poor infinity stop, similar to my AI 200mm f/4 which has impressive sharpness up to maybe  200m distance, but set at the infinity stop only gets sort of hyperfocal blur circles on stars....

I know you addressed Bjørn but my answer is:

You are judging the sharpness at distance by turning the lens until it hits the infinity stop...This is a very wrong approach to check how sharp a lens really is.
You will have a hard time evaluating you lenses, most likely they are completely fine! All of them… 
Also infinity is adjustable on all Nikkors – But also remember that infinity is infinity, far far away… not just down the road – especially for the sharp lenses it’s more critical.
Please use live view and a solid tripod/head.
Also, as has been hinted; Find another test target than a retina screen 