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Optical Design value Analysis - NIKON NIKKOR Z 58mm f/0.95S Noct[No.022]

This is a performance analysis and review article of the Nikon Nikkor Z 58 0.95 S.

You hardly know how the lenses work, how their performance differs from each other, and the specific differences between them.

Even if you check magazines and the Internet, you probably only find similar "word-of-mouth recommendation information" articles like that, don't you?

In this blog, while researching the history of lenses and their historical background, we estimate lens design performance based on patent information and actual shooting examples, and analyze lens performance in detail from a technical viewpoint through simulations.

Professional lens designer Jin Takayama will carefully unravel optical characteristics such as optical path diagrams and aberrations that are not generally visible, and explain the taste and descriptive performance of lenses in a deep and gentle manner.

You may find a good lens, a bad lens, a famous lens, a peculiar lens, or a lost lens for you.

Please enjoy the special information that you can read only on this blog.

Unfortunately, we do not plan to prepare example photos.

Overview

In commemoration of the discovery of the NIKKOR Z 58mm f/0.95 S Noct patent documents, we have decided to proceed with a series of analyses of the NIKKOR 50mm. In short, this is a project to enjoy the history of NIKON lenses on my own.

First of all, as of 2020, the following NIKON 50/58mm lenses are currently available.

  • AI AF NIKKOR 50mm f/1.8D
  • AF-S NIKKOR 50mm f/1.8G
  • AI AF NIKKOR 50mm f/1.4D
  • AF-S NIKKOR 50mm f/1.4G
  • AF-S NIKKOR 58mm f/1.4G
  • Ai NIKKOR 50mm f/1.2S
  • NIKKOR Z 50mm f/1.8 S
  • NIKKOR Z 58mm f/0.95 S Noct

Eight of them…that's a menace. And each of them seems to have a different optical system.

It is understandable if the motors, drive mechanisms, electromagnetic aperture, etc. are different, but why bother to change the optics as well?

In the previous article, we analyzed NIKON's first full-size mirrorless standard lens, the Z 50mm f/1.8S, and were impressed by its extremely high optical performance.

This time, we will analyze the ultra-large aperture 58mm f/0.95 for mirrorless lenses, which is also the last in the series.

Fno indicates the brightness of an optical system and is usually expressed as a power of √2 (≈1.4).

When the focal length is the same, an Fno one stop smaller means that the area of the aperture viewed from the front of the lens is twice as large, or 1.4 times larger in diameter.

The characteristics of a lens are expressed in terms of a parameter called aberration, which simply refers to the ability to focus light to a very small single point.

The general Fno notation is as follows in descending order of darkest to darkest, in one-step increments.

 Fno32 22 16 11 8.0 5.6 4.0 2.8 2.0 1.4 1.0

The difference between Fno1.4 and Fno1.0 seems to be only 0.4, but the area is twice as large.

You can see how difficult it is to correct for aberrations with a larger F1.0 lens.

Private Memoirs

This lens was announced in development in 2018 at the same time as NIKON's entry into the full-size mirrorless market, and was hinted at from the beginning, but was released almost a year later in October 2019 with a shocking size and price.

MSRP 1,265,000 yen($9,425.89), made-to-order, no autofocusing. It is manual-only.

The weight of this lens is 2Kg, which I can only assume is a joke, but my guess is that NIKON thought that such a lens was necessary to demonstrate the significance of the new Z mount and the new full size mirrorless system that has finally been introduced.

After all, they were talking about the unchanging F-mount until recently, so they can't just back off now.

They are trying to cover it up by coming up with something outrageous. (Probably).

However, the size and price of the product is so extraordinary that there is no doubt that the performance will be a shock to you.

I don't think I will ever be able to get my hands on an actual lens, but I would love to try shooting models with a lens like this.

Document Survey

I thought that a patent for this product would not be applied for. The primary purpose of applying for a patent is to prevent other companies from copying your product.

They would not imitate this product…normally. If we developed and sold a lens with such specifications, a normal company would go bankrupt.

NIKON is the world's leading manufacturer of lenses, so they can do what they do.

One day, when I had given up looking for patents, I suddenly found WO2019/229849, which I had not expected to find. There seems to be little difference between Examples 1 and 2, so let's reproduce it immediately using 1 as the design value.

Notes!

The following design values have been selected and reproduced from the appropriate patent literature and do not correspond to the actual product. Naturally, the data is not guaranteed, and I am not responsible for any accidents or damages that may occur by using this data.

Analysis of Design Values

Optical Path Diagram

Above is the optical path diagram of the NIKKOR Z 58 F0.95 S.

The lens is composed of 17 elements in 10 groups, with three aspherical lenses. It also has 4 ED lenses made of a special low-dispersion material to correct chromatic aberration, so it probably has all of the latest technology available today.

However…

The curse of the Gaussian lens cannot be broken, and the strongly curved concave surfaces in front and behind the aperture face each other, leaving a Gaussian-like configuration.

Negative focal length lens groups are placed on the subject side of the Gaussian configuration in front of and behind the aperture, and positive lenses are placed on the image sensor side of the Gaussian configuration.

The SIGMA Art 50mm f/1.4 is more similar to the Z50mm f/1.8.

Longitudinal Aberration

Graphs of spherical aberration, image surface curvature, and distortion

Spherical Aberration , Axial Chromatic Aberration

Spherical aberration and axial chromatic aberration are corrected to a perfect level.

The price of 1.2 million yen is no exaggeration. Even if we ignore the selling price, it is doubtful that we could reach such a high level of performance.

Image Surface Curvature

Image curvature is also extremely well corrected in line with spherical aberration.

Distortion

The symmetry structure of the Gaussian has been changed so that the shape of the distortion is no longer a simple barrel shape, but the absolute value has been corrected to a minimum.

Chromatic Aberration

Magnification chromatic aberration is also well corrected with little change at high image height.

Transverse Aberrations

(Left)Tangential direction, (Right)Sagittal direction

Let's look at it as a lateral aberration.

Sagittal halo is also very small, and it is hard to believe that it is f/0.95…

There is a little flare in the g-line (blue), but it is not a problem in actual shooting because of the low visual sensitivity.

It is possible that a product of this class might be made of glass with custom-made characteristics, and that the chromatic aberration might actually be much lower.

The patent data alone does not disclose that much. We would like to confirm this by taking actual photographs, but it may not be possible due to budget constraints.

Spot Diagram

Spot Scale 0.3 (Standard)

Here are the results of the optical simulation, but let's start with the spot diagram.

As you can see in the lateral aberration, there is some g-line (blue), but the rest of the aberration is small.

Spot Scale 0.1 (Detail)

Here is an enlarged view with the scale changed

MTF

Maximum Aperture F0.95

Finally, let's check the results of the simulation with MTF.

Let's reproduce the MTF of Z58 0.95.

It is tremendously high from aperture fno…
I thought Z50mm f/1.8 is also a good lens, but it is comparable. Now that's f0.95…

Small Aperture F1.4

It is too high from the maximum aperture, so there is little change at F1.4, which should have been stopped down one stop… It is a high performance that should be impressive, but my senses are completely numb.

Small Aperture F1.8

The image is crisp and aberration-free all the way to the extreme edges, and is nearly aberration-free at f/1.8. There will be no difference in a good sense even if you stop down any further.

Small Aperture F4.0

Using this lens at f/4.0 is an act that only the most extravagant of Arab oil tycoons would be able to pull off.

Conclusion

In the past, we often saw a pattern in which a large aperture lens with a bright f/number was outperformed by a small aperture lens with a darker f/number, but this lens is an ultra-large aperture lens with ultra-high performance from wide aperture.

The Z50mm F/1.8 had shockingly high performance, but NIKON has achieved a performance comparable to it at F0.95. Even if it is to show the significance of the existence of full-size mirrorless lenses, the general public can only sigh…that's too much.

Well, this is the end of the series of articles analyzing all NIKON 50mm lenses.

Unfortunately, we could not find a patent for the 50mm f/1.2, and I think it may not have been eligible for patent digitization at the time. The lens looks similar to the Zuiko 50 f/1.2 in terms of configuration, so I think it will have a similar performance.

I have finished the individual analysis, but I will continue to create articles for comparative analysis.

I don't think there will be an example page.

Sample Picture

Example photos are in preparation.

If you are looking for analysis information on other lenses, please refer to the table of contents page here.

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