When did Nikon stop handgrounding their lenses?

[Imagelover]

On YouTube there are much talk about micro contrast on older lenses. Micro contrast is often used in conjunction on lenses with few lens elements. Can anyone please tell me when Nikon did stop handgrounding their lenses? Thanks.

[Akira]

Well, I would guess that Nikon has never hand-ground any lens elements, at least for their S- or F-mount cameras.

According to the "1001 Night", Even the extremely aspherical element for the OP 10mm/f5.6 fisheye was ground by the then state of the art NC machine and only "hand-polished".

FWIW, I'm big fan of simple optical designs for not a scientific but more of a spiritual reason.

[pluton]

On YouTube there are much talk about micro contrast on older lenses. Micro contrast is often used in conjunction on lenses with few lens elements. Can anyone please tell me when Nikon did stop handgrounding their lenses? Thanks.

A few years ago, there was attention-getting trope in the photo equipment media promoting the idea that lenses that are comprised of fewer elements are 'better' or 'nicer' or 'have more micro contrast' or 'have more 3D pop'. 
It was discussed here at Nikongear:
https://nikongear.net/revival/index.php?topic=2916.0
https://nikongear.net/revival/index.php?topic=6628.msg106344#msg106344
 
Here's a film that shows machines grinding lenses in 1944, supposedly shot at a Nippon Kogaku factory:
https://www.youtube.com/watch?v=GfDwlKMyboE

[Birna Rørslett]

"Better" is a difficult property to evaluate, as it always has to be understood and interpreted in a defined context.

Older lenses in general are less sharp than their modern equivalents (in terms of focal length and aperture). For some purposes that is a positive and attractive characteristic. In other settings, not so much. The same goes for their tolerance towards flare and ghosting. Smaller size might be another area of interest to the end user. And some of us actually like, to the extent of preferring,  the feel and build of vintage lenses.

[Roland Vink]

The OP Fisheye-NIKKOR 10mm F5.6 was introduced in 1968, the first lens with an aspherical lens, well before CNC polishing was available. From the 1001 nights article:

"There are better processing technologies these days, but back then, direct-molding technology has made it easier to volume-produce small-diameter aspherical surfaces, but careful finishing was required after grinding. NC (Numerical control) machine tools can now fabricate aspherical surfaces easily, but then craftsmanship was an important part of every lens."

The next Nikkor with an aspherical lens was the 58mm Noct from 1977, also before CNC was possible. Like the OP Nikkor, the aspheric lens would have been carefully cast in shape and then ground and polished "by hand" by a skilled technicial to achieve the final surface:

"Moreover, it is essential for a high precision lens to be inspected with high precision. In the case of the Noct NIKKOR, it is needless to say that an aspherical lens element was measured its surface shape. In order to control amount of flare of each product, the assembled lens was measured aberration by a special inspection instrument in addition to a routine inspection of resolving power test"

All aspheric lenses since then, have been created using CNC machines to grind and polish the lens, or glass moulded, or hybrid (aspheric plastic surface molded on a conventional lens).

As for conventional spherical lenses, maybe very early lenses from the 1950s and before had a high degree of manual input, but most lens production has been mechanized for a long time.

[Toby]

I would take with a grain of salt all this talk of "microcontrast" and "3D pop" of older lenses. There is a lot of nonsense out there. One of the main reasons that older lenses limited the number of lens elelments was the light lost at each air to glass surface due to reflection. Modern coatings have reduced light loss and scattering tremendously and thus made possible the use of many more elements to reduce aberrations and while still maintaining very good contrast and light transmission. I am a great fan of old lenses and have more than I care to admit, but I do not use them because of any kind of superior contrast or sharpness. I use them wide open because of their optical characteristics--their "bokeh", which can give a very unique look in out of focus areas. It is certainly true that many older lenses perform adequately in terms of sharpness and contrast when stopped down, but for general photography I will go with modern lenses every time. Yes, there is a wonderful feel to many old lenses, made of metal, with smooth and velvety focusing helicoids and solid-feeling aperture rings, but in very close inspection of images, almost none of them can hold a candle to decent modern lenses, even zooms.

[Akira]

The OP Fisheye-NIKKOR 10mm F5.6 was introduced in 1968, the first lens with an aspherical lens, well before CNC polishing was available. From the 1001 nights article:

"There are better processing technologies these days, but back then, direct-molding technology has made it easier to volume-produce small-diameter aspherical surfaces, but careful finishing was required after grinding"

Ooops, I might have some difficulty in understanding Japanese.   

That said, I guess the translation was not perfectly complete.  In the last sentence quoted above, the original Japanese text says "after grinding 'with the processing machine'".  So, the aspherical front element of OP fiseye 10mm/f5.6 was not completely hand-ground.

[Roland Vink]

"Hand grinding" conjures up images of a technician with a lens on some sort of lathe, carefully shaping the lens with various grades of sandpapers by hand to achieve the desired surface . I am sure even in 1968 it was much more sophisticated than that, and without Computer Numerical Control (CNC) methods they had very precise mechanical machines to help them with the process.

[chambeshi]

Stand to be corrected, I have read injection-molding was the big step forward in precision and mass production of aspherical optics? Kodak began molding plastic aspherical elements many years ago, but it took refinements in CNC to tighten the precision and mold optical glass. The relevant information may well be in a 1001 Nights essay (or more than one).

And is not high precision injection-molding the keystone that enables production of the phase-fresnel elements in the 300 f4E PF and 500 f5.6 PF?

[Roland Vink]

The first aspheric lenses were probably made from molded glass which were then carefully ground and polished to the final shape in a very labour intensive process - 58mm Noct and 10mm OP-Fisheye.

The next aspheric lenses to appear were the hybrid lenses, which have a plastic aspheric surface molded onto a regular spherical lens. This first appeared on a Nikkor with the AF 28-70/3.5-4.5 in 1991 and then other lower and mid-range lenses. These elements tend to be small and not radically aspheric. The high cost of producing the dies is offset by their long life - plastic is softer than glass so easy to mold and the dies don't wear out.

Next came CNC ground glass aspheric lenses, found in the AF-D 28/1.4 and AF-D 20-35/2.8 from 1993. This is basically a modern, computer controlled version of the early aspheric lenses. Computer control allows for much higher production with greater consistency, and can create aspheric lenses with complex shapes and relatively large diameter.

Molded glass aspherics were the last to appear, and probably needed the development of new types of glass which could be molded accurately without distorting when cooled down. It probably also required new technology to create the dies with sufficient precision and durability. The first Nikkor with a molded glass lens was the AF-D 18/2.8, but really took off with the introduction of lenses like the AF-S 28-70/2.8 and AF-S 17-35/2.8 in 1999. These lenses feature large diameter aspheric lenses with a complex shape.

I'm not sure how phase-fresnel elements are made but given their shape I guess they are molded as you said.

[chambeshi]

Hi Roland
Thanks for all the data rich information. Slightly off topic, the challenges in producing the wide PF element appear to underlie the hold ups behind the scarcity of the 500 PF.

All considered, we are fortunate to live in these times with the benefits of these impressive technologies. It seems to be the exception for the latest normal and wide angle primes, (also zooms) not to include at least one aspherical element. Of the Z Nikkors announced so far, the only two without aspherical elements are the longer 85 f1.8S and 50-250 f4.5/6.3 VR DX. The tiny 16-50 DX has 4 /9

kind regards woody

[dibyendumajumdar]

Hi,

I believe Canon had mass production tech for aspherical lenses in the 70s. Hence Canon had a quite a few aspherical lenses in their FD system.
https://global.canon/en/imaging/l-lens/technology/aspherical_lenses.html

Ground aspherical lenses came before lenses with resin/plastic add-on. Moulded lenses are the very latest I believe.

Regards

[dibyendumajumdar]

I should add that the first aspherical lens for 35mm cameras was the Leica Noctilux 50mm f1.2 introduced in 1965.

Regards

[Macro_Cosmos]

Microcontrast is MTF50, nothing more and nothing less. I'm guessing the source would be a rather popular youtube guy who also likes to talk about magnetic fields.

The talk about "better rendering" from low element count lenses is purely subjective. Each lens would have different rendering depending on the optical formula, more or less lens elements won't affect that "3D pop" or whatever it's supposed to mean. Is it scientifically quantifiable? If so, please show me. (I'm being nice here, I usually call this notion... and refer to this as the cult of contrast).

I'll go so far as to say the so called "3D pop" is due to field curvature, ie low element count lenses are generally less corrected, unflat, therefore the image seems to bounce out. A person who owns many lens design patents, who's also behind a popular lens company does agree with me, so there's that. He also claims the "low element count colours" or referred to as 德味 (German taste) can be easily mimicked with lens coatings. So the notion of "low elements produce more vibrant colours" is also a product of premature coatings altering the true colours. He's a bit secret with his real identity, so I will respect it. If I did post a name though, expect to find some of his patents on Japanese sites for various big companies.

Whether you like the vibrant colours or want them realistic and flat, whether you like field curvature causing images to pop or you want a better and more corrected lens, all is valid. Just buy whatever you like. 

Which one pops more?



This is a controlled test by the way, both lenses have low element count.
The first comes from the Printing-Nikkor 105mm F/2.8A at F3.3 and 1x.
The second comes from the Schneider Xenon-Sapphire 3.9/95-0001 at 1x, this lens is optimised for 0.23x, so pushing it to 1x mounted forward is using it out of spec. As a product of that however, more field curvature is brought in, resulting in corner fuzziness and therefore the centre "apparently" pops out. That's just my perception.

Back to your question, I don't think Nikon ever hand ground their lenses. If they did, I don't know about it. They however used to hand polish lenses, the legendary 28mm F1.4D and 20-35mm F2.8D feature hand polished aspherical elements.

[Toby]

I believe that the first aspheric element in a mass produced lens was in the Kilfitt Makro Kilar 90mm f2.8. However the technology did not exist at the time to make a smooth surface, so the element had a step where the radius changed, giving it a very unique bokeh