The Ultimate Guide to the NIKON NIKKOR Z vs F 50mm F1.8 - Optical Design Value Analysis No.051

This article is a performance analysis and review of the Nikon Nikkor Z 50mm F1.8 and Nikkor F 50mm F1.8.

You hardly understand the specific differences in how the lenses work and how their performance differs from each other, do you?

Even if you look it up in magazines or on the Internet, all you will find are similar "word-of-mouth recommendations" and articles like that.

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, which are generally not visible, and explain the taste and descriptive performance of lenses in a deep and gentle manner.

Now, please enjoy the special information that you can read only on this blog in the world.


Although the NIKON 50 mm F1.8D is the standard lens for Nikon F-mount cameras, it was originally developed as the E-series, using optics that have been on the market since 1978, and was discontinued in 2013.

Until around 2018, new products were generally distributed in the market, but as of 2021, it seems that it has become difficult to obtain new products except for some online shops.

The NIKKOR Z 50 mm F1.8S, on the other hand, is a new-age standard lens that appeared in 2018 for Nikon's first full-size mirrorless single-lens Z-mount camera.

The demise of the NIKON 50 mm F1.8D is like watching the rise of Nikon's full-size mirrorless and quietly ending its life as if it were an old samurai.

This time, as a memorial to the NIKON 50 mm F1.8D, I would like to compare and verify the new and old standard lenses again.

Private Memoirs

We analyzed these two lenses in the early days of the blog.

Just in the midst of the corona turmoil in 2020, as a private self-control activity, we carried out a series project to analyze all NIKON 50 mm lenses. (It was really painful.)

Please refer to the following for each article.

Also Read: F Mount NIKON 50 mm F1.8D
Also Read: Z Mount NIKON Z50mm F1.8S


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, the left is the optical path diagram of the NIKON Ai AF NIKKOR 50 mm f / 1.8D and the right is the optical path diagram of the NIKKOR Z 50 mm f / 1.8S.

At the time of writing this article, we re-created the optical path diagram with the same scale ratio.

The F-mount 50F1.8D is a variant of the traditional Dowble-Gauss configuration.

For the double Gaussian type, please refer to the detailed article below.

Double Gauss Lens

On the other hand, the Z-mount Z50F1.8S has an arrangement in which the front and back of a double Gaussian lens are surrounded by a group of concave lenses. It is presumed that this is the invention of a symmetrical arrangement in the new era that symbolizes the era of full-size mirrorless.

Longitudinal Aberration

Graphs of spherical aberration, image surface curvature, and distortion

Spherical Aberration , Axial Chromatic Aberration

For the longitudinal aberration, the NIKON Ai AF NIKKOR 50 mm F1.8D is placed on the left and the NIKKOR Z 50 mm F1.8S is placed on the right.

Looking at the spherical aberration, the F-mount 50 F1.8D has a traditional full-correction aberration shape that bulges to the minus side, while the Z-mount Z 50 F1.8S has an aberration shape that is almost straight.

At the time of announcing the development of the F-mount 58 mm F1.4G, we were advocating a three dimensional high-fidelity optical design in pursuit of "taste and resolution of depiction", but if you look at the Z 50 F1.8S, you can see that it was developed with the aim of zero aberration as much as to say, "that!"

Also Read: NIKON 58 mm F1.4G

It is probably to show off a new lens called mirrorless that is suitable for the new era.

I wonder if it has become about 1/5 even in axial chromatic aberration. I am worried about what to do in the future after making it so good.

Field Curvature

Similarly, field curvature's Z-mount Z 50 F1.8S has an aberration shape like a straight line.


Similarly, the Z-mount Z50F1.8S has an aberration shape similar to a straight line.

With a 50 mm F1.8 lens, each aberration can be kept so small that the person in charge of the design cannot help but worry that there may have been some kind of trauma.

Lateral Chromatic Aberration (Magnification Chromatic Aberration)

The lateral chromatic aberrations of the Z-mount Z 50 F1.8S is worse from around 18 mm around the screen.

Nikon has also announced that it will use image processing to correct lateral chromatic aberrations in the F-mount camera, so the Z-mount camera may be planning to use more image processing.

Transverse Aberrations

(Left)Tangential direction, (Right)Sagittal direction

Let's look at it as a lateral aberration.

The Z-mount Z 50 F1.8S has dramatically reduced the sagittal coma flare that is the taste of the picture.

It is absolutely right physically, but it is a complicated state of mind with a little loneliness.

Spot Diagram

Spot Scale 0.3 (Standard)

Now let's look at the optical simulation results, but first let's look at the spot diagram.

The spot size has also been greatly reduced: the spot size at the corner of the screen on the Z-mount Z 50 F1.8S is smaller than the spot size at the center of the screen on the F-mount 50 F1.8D.

This is a shocking aberration correction technique.

Even if you say, "You can design as you like," it is difficult to correct to this extent.

You can't do it without crazy discipline and design sense.

Spot Scale 0.1 (Detail)


Maximum Aperture F1.8

Finally, let's look at the results of the MTF simulation.

As you can see in the spot diagram, there is only a slight difference between the screen corner of the Z-mount Z 50 F1.8S (the height of the peak of the red line) and the screen center of the F-mount 50 F1.8D (the height of the peak of the blue line).

Incredible levels of performance.

Small Aperture F4.0

Due to the excellence of the Gauss lens, when you narrow it down to F4, the F-mount 50F1.8D plays pretty well, but it still seems to be one step behind the Z-mount Z 50 F1.8S.


If you compare the two lenses side by side again, you can see that the F-mount 50 F1.8D has the typical aberration characteristics of a classic double Gaussian lens, but the Z-mount Z 50 F1.8S has already achieved aberration correction at a different dimensional level.

It is sad, but with the appearance of the Z-mount Z 50 F1.8S, the F-mount 50 F1.8D has finally finished its role. you can see it well.

However, it is also true that the depiction performance of the F-mount 50F1.8D is irreplaceable.

I sincerely hope that it will be reissued on Z-mount as well.

Until then, I would like to secure F mount 50F1.8D.

Sample Picture

Please refer to the individual analysis page below for the sample photos.

Also Read: F Mount NIKON 50 mm F1.8D
Also Read: Z Mount NIKON Z50mm F1.8S

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

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