Film Scanner Lenses for Focus Stacking Part 3 – Scanner Nikkor ED 100 (Nikon 14 lenses)

High-quality film scanner lenses have ideal properties for detailed shots using focus stacking. Here, the last of three lenses is presented.

Film Scanner Lenses are ideal for capturing  a flower blossom, the body of an insect and other delicate objects in a complete and high-resolution manner.

Photography with focus stacking fascinates in two ways: on the one hand, with what can be seen through the lenses, and on the other hand, through the lenses themselves. At least that's how I see it. This enthusiasm for lenses may be one of the reasons why it is appealing to discover film scanner lenses for this type of macro photography, as it takes you off the beaten path.

First of all, I want to discourage anyone from disassembling a functional film scanner to use the lens. On the contrary! My goal is to breathe new life into the heart of a dead film scanner, as some of them contain a real super-optic, calculated with the highest expertise, apochromatically corrected, optimized to the limits of physical laws, and superior to any conventional camera lens in many ways. Such super lenses often end up as electronic waste! And they simply don't deserve that!

Additionally: The challenge of adapting such lens cylinders without threads or bayonet mounts to the camera and testing their optimal usage conditions – aren't these the challenges many of us seek? Instead of just grabbing something from the dealer's shelf, we must understand the optical effects of their lenses and begin to comprehend them – and this could be a highlight for some of us in this hobby. But now to the subject…

Three legendary film scanner lenses: on the left "Minolta Dimage Scan Elite 5400", in the middle "Scanner Nikkor ED 7 Element Lens" and on the right the large "Scanner Nikkor ED 100" with 14 lenses, the gold standard for 1:1 shots with focus stacking

After the two absolutely legendary film scanner lenses, the "Minolta Dimage Scan Elite 5400" and the "Scanner Nikkor ED 7 Element Lens," I introduce another lens here, which I consider to be the absolute top class: the Scanner Nikkor ED 100. It would be a great pity for each of these optics that ends up in the trash with a scrapped film scanner. I compared it myself to the equally legendary Leica Apo-Elmarit R 2.8/100 macro lens, a masterpiece by Wolfgang Vollrath, which is still considered one of the world's best macro lenses more than three and a half decades after its market introduction in 1987. The result: It is significantly superior to it in terms of image sharpness and color reproduction – almost unimaginable if you know Leica's Apo-Elmarit.

A lens with good genes

However, the Scanner Nikkor ED 100 also has exceptionally good genes: It was developed based on the equally legendary Printing Nikkor 95 mm, which Nikon developed around 1970 for extremely high-quality reproduction purposes, e.g., in the printing industry, but also for copying cinematic films. No effort was spared to develop the best possible optics, regardless of the cost, as the purpose justified the means, even financially. Nearly three decades later, Nikon rediscovered this legendary optic and decided to develop two film scanner lenses based on its lens calculations. The smaller one was presented in part 2 of this series, and the focus here is on the larger one.

Nikon Super CoolScan 8000 – the home of the legend ...

The home of this magical lens is the Nikon film scanner Super Cool Scan 8000, designed primarily for scanning medium format films in addition to 35 mm films. Shortly after, Nikon replaced this scanner with the Super Cool Scan 9000 model, which cost around $1,000 less but was comparable in most respects. Nikon made significant efforts to optimize cost structure and also made changes to the lens, especially since the EU criticized toxic substances in some lenses, leading to their replacement with non-toxic materials. However, the image quality of the lenses in the 8000 and 9000 models is practically identical.

Extensive lens development

Some speculated that Nikon simply adopted the lenses of a newer version of the Printing Nikkor, namely the P.N. 105 mm f/2.8 A. However, this is incorrect, as Enrico Savazzi writes (pls. see below), and it made little sense because the tasks of a high-quality film scanner are very specialized.

Not only does the film scanner work through a thin glass pane that protects the scanner sensor, for which the printing Nikkor was not optimized. The dust and scratch removal during the scanning process in such a film scanner requires lens adjustments. This involves a separate scanning process with infrared light. This radiation passes through the film unhindered, but scratches and dust particles on the film block this extremely long-wavelength radiation, enabling their identification and elimination from the image. Marco Cavina (pls. see below) points out that NIR radiation (near-infrared radiation) at 850 nanometers is used for dust detection. Consequently, certain lenses of this scanner lens must be corrected into these very long-wavelength ranges.

The Printing Nikkor 100, on the other hand, was used for reproduction purposes and cinematic film copying, where dust removal was not carried out in this form. So it made little sense to simply adopt the lenses of a Printing Nikkor version unchanged for a film scanner lens. In fact, this lens involves intense development work, leading to three legendary prototypes, as reported in detail by Marco Cavina.

Lens overview image Scanner Nikkor ED 100 (Source: Nikon company brochure)

In the Scanner Nikkor ED 100, the exceptional correction of the lenses was adopted from the original Printing Nikkor 100. It is an ultrawide-band apochromat, with lenses perfectly correcting astigmatism, spherical aberrations, image distortions, and lateral chromatic aberrations across the entire image circle, not only in the visible light range (400–780 nanometers) but up to 850 nanometers, i.e., into the near-infrared range.

Discovering this fantastic film scanner lens for focus stacking photography is solely the merit of the late photographer Robert O'Toole, who described it on his website as having "blurred the line between what could be achieved with an affordable desktop scanner and a professional drum scanner," and: "When the Nikon 8000 ED scanner was announced in 2001, there was literally no comparable lens on the market.“

Since he reported on this lens in 2017, the price has skyrocketed, not least because it is rarely offered. Since manufacturers have stopped production and distribution of the devices and even spare parts supply, the value of functional film scanners has increased rapidly, and the situation in medium format is even more dramatic. Even when searching globally through online auction houses, it is extremely rare to find a Nikon Super CoolScan 8000 or 9000 being discarded and filleted, and countless interested parties worldwide have saved the search in their online profiles and are just waiting for it.

The Scanner Nikkor ED 100 has numerous scratch marks, which were important as alignment marks during mounting. Above you can see the white paint dot that was oriented towards the sensor in the scanner.

Housing and magnification ratio

The Scanner Nikkor ED 100 has 14 lenses arranged in six groups. A look at the two main groups, which appear nearly identical and mirror-symmetric, suggests that this lens can be used in both directions. In fact, this is true, but with slightly different magnification ratios, as in the original position (white dot on the housing pointing towards the sensor), it operates at approximately 0,9:1, while in the reverse direction (white dot on the housing pointing away from the sensor), it operates at approximately 1,1:1. Robert O'Toole provides magnification ratios of 0.87–0.89 for the sensor position and 1.12–1.15 for the reverse direction.

Determining the image scale

Sensor 35 mm full format, image width 36 mm; modify the focus distance (distance between sensor and light exit lens of the objective) so that you can see a certain number of millimeters on a focused ruler with millimeter graduation.

The image shows 36 mm = 1:1

The image shows 32.4 mm = 1.1:1

The image shows 39.6 mm = 0.9:1

To determine the optimal extension length, focus on a millimeter scale and observe the number of millimeters visible in the image that corresponds to the width of your sensor, i.e., 36 mm in full-frame format. Then you are working with 1:1 and can vary according to the direction of the lens. Working at 1:1 is unproblematic. If you stretch the extension length to achieve 2:1, you may have to compromise on image sharpness.

The housing consists of several cylindrical elements, with the middle one having the largest diameter. The two slender ends are of different lengths, and the longer one bears the white dot, indicating the direction towards the sensor in the scanner. By carefully examining the width and number of annular housing elements, one can also easily distinguish between the 8000 and 9000 versions.

The front, rear, and middle cylinder diameters are identical in both models and measure around 48.5 mm. I have this objective in a 50 mm inner diameter mount (pls. see below), which requires wrapping the barrel with a layer of thin cardboard strips.

Don't be surprised by the numerous scratches on the housing; these are markings that give an impression of the complex calibration and testing processes during lens assembly.

Full-frame suitability

This lens was designed for medium format films, which have a scan width of 63.5 mm. The active sensor area length (film scanner sensors are not rectangular with flat pixel arrangement like a digital camera, but rod-shaped and move from one side to the other across the film) is 57.5 mm. This means the image is slightly reduced during the scanning process in the lens, around 0.9:1. Consequently, the lens is optimized for magnification ratios around 1:1 and performs best in this range. The image circle diameter of 57.5 mm far exceeds the full-frame diagonal of 43.5 mm, making this lens absolutely suitable for full-frame use.

The sensor of this scanner, which operates behind a thin glass plate, is rod-shaped and active over a length of 57.5 mm (red bars)

The image circle of this lens is so huge that it far exceeds the diagonal of a full-frame sensor. If this lens had any aberrations in the peripheral area, they would not be visible in the photo. However, it is absolutely free of aberrations of any kind...

Image quality

The image quality of this lens is fantastic and is similar to that of its little brother, the Scanner Nikkor ED 7. Only the correction of aberrations in the peripheral area of the ED 14 is probably a little better, but this would probably only be measurable, hardly visible and would mainly take place in the outer areas of the image circle, which are no longer imaged with the full-frame sensor anyway. The image is sharp from the center to the corners, free of distortion, and there are no chromatic aberrations. The color rendition is breathtaking. And the working distance for focus stacking work is nothing short of regal, because at 1:1 it is more than 13 cm!

The main advantage over the Nikkor ED 7 scanner is that in full format, image scales of 1:1 and slightly below are also possible with optimum image quality, because this lens has been optimized precisely for this purpose, whereas the smaller ED 7 has been optimized for a scale of 1.33:1, so in full format its best performance is at 2:1 while it produces slightly darkened corners in at 1:1. So if you always want to work in the sweet spot of the lenses, use the ED 14 for 1:1 and the ED 7 for 2:1. However, the ED 14 also covers a scale of 2:1 without any noticeable loss of quality. Only at 3:1 do you have to reckon with the corners becoming somewhat soft.

Wing scale image of the butterfly Chrysiridia rhipheus (1:1, unprocessed image file), the red frame shows the following image section

This tiny image section shows the image quality of the Nikon ED 14

Objective Removal

Removing the objective from the scanner is significantly more difficult than with the Minolta Dimage Scan Elite 5400, but still much easier than with the Nikon Super CoolScan 5000 and its close relatives.

First, remove eleven philips screws on the back.

Next, pull the casing back and upward.

When you look at the right side of the scanner, you'll see a large, matte black complex made of plastic – this is the component you need to remove to access the objective from below.

Start by unscrewing the front panel (four crosshead screws, two on the left and two on the right).

Then unplug the cable from the circuit board, located on the left behind a metal panel. Then you will see another connecting cable between this circuit board and another on a metal bridge over the component in question. Unplug this cable from one end, but the metal bridge remains on the black component, the heart of the scanner.

Next, you can remove four philips screws in the lower area that connect to the bottom plate of the casing.

Now pull the connecting rod of the power switch at the rear end out of the anchor on the switch on your circuit board. Be careful, the plastic part is easily breakable.

By now, unplug two flat connectors from the circuit board.

Deep down near the bottom, you will find three more flat connectors that need to be unplugged.

Now you can lift the entire black plastic complex to turn it over.

Here is the scanner objective, firmly anchored in a bowl-shaped recess. In the image, you can see condensation moisture on the objective due to temperature; never wipe this off the lenses; the droplets will evaporate without a trace.

Now you can unscrew the bracket, leaving the objective exposed.

To remove the objective, you only need to remove the four screws from the cover plate. (It would be better to remove the cover plate first while the holding bracket is still in place; I proceeded differently in this case).

Then carefully place both hands under the objective without touching any of the lenses and gently pull the tightly clamped objective out of the scanner.

The asymmetry of the objective housing helps in determining position: you can see that the longer-appearing part of the housing faces the mirror from which the light signal comes, while the shorter-appearing part, which also carries a white marking point (camera-facing), faces the sensor.

Attachment to the Camera

There are several options for attaching this objective to the camera.

Rafael Pankratau (RAF Camera, rafcamera.com/) offers a specially designed adapter for this objective with an M42 (male) thread. This allows you to directly connect to appropriate adapters for your camera.

RAF objective adapter with M42 thread.

An alternative is a threaded sleeve with a 50 mm inner diameter and 52 mm outer thread recommended by Robert O'Toole. It is available from Thorlabs and fits perfectly over the objective. Similar sleeves can also be custom-made by lathe specialists like Rainer Ernst (www.stonemaster-onlineshop.de).

With the appropriate base plates, different objectives can be attached to the Balpro 1 bellows device.

I chose the RAF adapter because I can use a special iris diaphragm adapting from M42 to M39 on a suitable base plate of the Novoflex Balpro 1 bellows device. This holding plate can be very easily removed with two retaining screws and exchanged for others that, for example, carry Mitutoyo or HLB objectives, or the Minolta 5400.

Aperture

Unlike all versions of the Printing Nikkor, the Scanner Nikkor ED 100 has no aperture. However, the sharpness of the image from this objective can be slightly enhanced if an aperture is present and properly adjusted. Such variable lamellar apertures are available with an M42 thread, female on one end and male on the other, and the RAF Camera adapter fits perfectly onto such an aperture, which, for example, can be found on Rainer Ernst's website (www.stonemaster-onlineshop.de).

Adjustable iris diaphragms are available with M42 or other threads.

An adjustable iris diaphragm can slightly increase the sharpness of the image. However, the optimal aperture setting must be marked on the housing.

However, you should be careful not to produce diffraction blurs. By default, the objective has a numerical aperture of f/2.8. Robert O'Toole (personal communication) recommended placing a variable aperture behind it and setting it to f/3.5 to slightly increase image sharpness and contrast. The aperture opening in millimeters corresponds to the ratio of focal length to aperture number, in this case:

Focal length in mm : aperture value as a number = aperture opening in mm

100 : f/2.8 = 35.71 (numerical aperture without variable aperture)

100 : f/3.5 = 28.57 (added variable aperture set to f/3.5 or 28 mm)

The Scanner Nikkor ED 100 in a ready-to-use configuration including a variable aperture

With a bellows device, the imaging scale of this objective can be excellently varied, and reversing the optics with the help of three Allen screws is very easy.

In my experience, the aperture opening can be even a bit smaller, but you should work on your own test series with comparison images of an appropriate subject to develop your interpretation of sharpness impression in the absolute limit range, as well as your tolerance for diffraction blurs.

Lens Hood

Robert O'Toole (personal communication) also pointed out the extreme sensitivity of this objective to stray light and recommended making an appropriate protective hood to clip on to prevent false light through reflections and further enhance color contrast. The easiest way to do this is with a piece of cardboard lined with a layer of black felt on the inside.

A lens hood can prevent false light influence and slightly increase color contrast.

Sources:

Robert O’Toole

https://www.closeuphotography.com/scanner-nikkor-ed-lens

Enrico Savazzi

https://www.savazzi.net/photography/scanner-nikkor-100mm.html

Marco Cavina

http://www.marcocavina.com/articoli_fotografici/articolo Scanner Nikkor ED.pdf