Fine-tuning a Noct Nikkor

[Airy]

My copy is fine, but for the focus shift.

According to a blog (Ming Thein's IIRC), some copies display focus shift but others not.
The shift is significant (to the effect that the focussed object slips outside the sharpness zone around f/2.8-f/4, then gets back when DOF increases further), so it is annoying in real photography. It makes me think that the spherical aberration is not fully corrected, a hint that some element inside may be misplaced (axially). On the other hand, the IQ wide open does not reveal loads of uncorrected aberration : contrast is very good (I'd say, as good, or better, than with the three other copies I had tested in the past, and for sure better than anything else - I also played with a f/1.1 Noctilux today, which definitely has less punch).

Bottom line : I'm happy with the lens, but I'd not hesitate to dish out some more money to get the best out of it, if anything could be gained.

Following Björn's advice, I contacted the Nikon support centre. They responded the same day that they stopped supporting the Noct, lacking spare parts (well, I was not asking for spare parts, just for fine-tuning). Then they suggested to contact three local (French) independent repair shops; only one seems to be qualified, but I doubt they would be able to fine-tune a Noct, probably lacking documentation about the procedure.

Does anybody have a suggestion ?

[simsurace]

You need a technician with a collimator and the skills to adjust the lens. There is someone in Switzerland who once adjusted one of my AI-s lenses, he could probably check it before opening it up. When I talked to him he revealed that most lenses are somewhat misaligned to a degree that is much larger than what he can detect. But I understand it is a question of how much time is put into calibration.

[Akira]

So far as I realize through my own humble experiences and review articles, fast lenses (f1.8 or faster) of the Gaussian design (or sometimes other designs) commonly suffer from the focus shift at around f2.8.

The workaround would be to use the live view where the aperture is stopped down to the set value or to focus on the OVF screen with the preview button pushed.  If the lens is stopped down to, say, f2.8, the screen would still be bright enough to judge the focus.

Idealistically I wish Nikon would enable the "stop-down AF" or "stop-down green-dot focus aid" to address the issue of any possible fast lenses.

[Airy]

Simone, indeed the question is about having the skills (I know guys with collimators, but they are Leicaists).

Akira, you are right about the general issue, but in this case, my Noct exhibits more shift than, say, the 50/1.2 despite being better corrected for sphericity aberration, so the situation looks paradoxical. I did use the LV workaround, but that's uncool for portrait sessions - better get some training at anticipating the shift (say, focussing on the tip of the nose, or approaching the focus point from the "short" side and trigger when focus is about to pop in) and leave the rest to statistical shooting.

In any case, be assured that I enjoy the lens; I'm not whining here, but just wondering how good it actually can become.

[longzoom]

Airy, it is not realistically you may put your lens in collimator. Nobody can today, I am afraid. You'll need a step-by-step optical compensation elements, at least 30 of them, to collimate your lens properly. Impossible today, to be descreet. The only solution for you, in case you described, is to choose most usable aperture, say, 2.8, and perform FT for this given aperture. So the combo will work acceptable in range of 2.0-2.8-4.0. Nothing else I may suggest, for this very old aspherical optical system. Sorry.  Good luck!  LZ

[Airy]

Thanks. Maybe I should consult Nikon JP and they could hire the retired fine-tuner who checked the last Nocts 20 years ago! and hand over the lens to my son who'll visit Japan next month. Haha.

I could not find any Noct huggers' club on the web. Just one +/- inactive dedicated website.

In the meantime, I saw other reviews (Lloyd Chambers....) mentioning and demonstrating significant focus shift, only one so far saying there was none. Anyway, I can live with it. I am very pleased by the wide open performance, which matters most. It is miles ahead of any other f/1.2-f/1.4 lens I currently own (high contrast, center sharpness), with the exception of the Voigtländer 58/1.4 that behaves the opposite way (low contrast, even sharpness). And Otus is not for me (size, weight, bulk).

[Bruno Schroder]

Airy, I would email Roger Cicala (Roger@olafoptical.com) at Olaf Testing (a spinof of Lens Rentals).  He most probably has the most advanced lens testing equipment available in the world. He was kind enough to answer my emails a few years ago and he is such a lens geek that he might even be interested in doing it.

http://www.olafoptical.com/home.html
https://www.lensrentals.com/blog/2016/11/testing-nasa-optical-lenses-how-we-measure-sharpness-and-accuracy/

[Erik Lund]

As far as I know, all Noct-Nikkor lenses where only serviced in JP due to the tolerances/design of the rear cell,,, the rearmost lens element is 'fused' into the housing so impossible to service that is why for instance service of a lens can lead to the need of a spare part no longer available,,,

[Airy]

Thanks Bruno and Erik, I'll give it a thought

[longzoom]

Thanks. Maybe I should consult Nikon JP and they could hire the retired fine-tuner who checked the last Nocts 20 years ago! and hand over the lens to my son who'll visit Japan next month. Haha.

I could not find any Noct huggers' club on the web. Just one +/- inactive dedicated website.

In the meantime, I saw other reviews (Lloyd Chambers....) mentioning and demonstrating significant focus shift, only one so far saying there was none. Anyway, I can live with it. I am very pleased by the wide open performance, which matters most. It is miles ahead of any other f/1.2-f/1.4 lens I currently own (high contrast, center sharpness), with the exception of the Voigtländer 58/1.4 that behaves the opposite way (low contrast, even sharpness). And Otus is not for me (size, weight, bulk).

       When my first - very old well-bitten Noct - vent out of alignment, I opened it, and was severely punished! The front group of elements was micro-adjusted by half-diameter  extra-thin washers, to fight the possible optical decentering problem. It took me about a week to fully understand and adjust the optical system anew. Then, I had to repair missed blades pins, so on, including helicoid. In two years, lens started to rise inner fog... So I cleaned it and put it to well deserved rest...  The absolutely new AIS version of this lens, second of mine, which I have never worked with, so never opened, just sitting inside the closet, in its own box! I'll keep them forever, for nostalgic reason. I did try Otus, for couple weeks. Really the best of the bests optical system, but manual... Very close to it, new Sigma Art, is fully workable for me, today. Yeah, long story shortly...  THX!  LZ

[Bruno Schroder]

Airy, there is a Noct repair manual here ; http://www.befr.ebay.be/itm/Nikon-Noct-Nikkor-58mm-F1-2-Ai-S-Lens-Service-Repair-Manual-/192195357317?hash=item2cbfbc6a85:g:2wMAAOSw3xJVZ-b0

[Airy]

Thanks !

Just purchased. That does not mean that I'll put it at a use. For the time being, I'll test my surgical powers on a damaged (non-usable) 50/1.8 AI. Maybe I'll become able to clean and re-lube a focussing helicoid (that's the most common case). A summer vacation job.

Since my Noct appears to be a good performer despite focus shift, I'll not attempt to "fix" it since it ain't "broke".

[Erik Lund]

The fine tuning of the lens elements is not dealt with in the repair manual,,,