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Telecentric Scanner-Nikkor ED LENS: Nikon 8000 ED lens
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RDolz



Joined: 28 Aug 2017
Posts: 73
Location: Valencia (Spain)

PostPosted: Mon Dec 24, 2018 9:33 am    Post subject: Telecentric Scanner-Nikkor ED LENS: Nikon 8000 ED lens Reply with quote

Hi all:

At Lou's request I show you the results of a Scanner Nikkor ED, which was removed from a Nikon 8000 Coolscan, but working in telecentric mode.

I have not checked the focal, so I put here the data from Robert's page, which mentions that it is a lens with a Focal length: 100 mm and a Nominal aperture f / 2.6. You can also see in detail how to integrate it into a photographic system:

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

I have made it telecentric with the method of mounting a diaphragm between the lens and the sensor. The diaphragm is about 40 mm from the back of the metal barrel of the lens. The diameter of the diaphragm is approximately 9 mm.



With a distance from the diaphragm to the sensor of 113 mm, the horizontal field of view is 21mm, which gives in the sensor of my Fuji X-T1, a magnification of 1,12X. Very close to its nominal magnification.

The length of the setup from the front of the lens to the sensor is 235 mm.
The working distance is 130mm.

The average telecentricity measured is excellent, 0.0041%, that is, 4.1 parts per 1000. It is considered telecentric from 0.02%, so we have that this setup is much better.

I have photographed a piece of pottery that I picked up on a beach near my house, a beach in Valencia. It is a curved ceramic, covered by tubes of polychaete worms (of the Serpulidae family) and bryozoans.
A complex three-dimensional structure ideal for checking the telecentricity and the quality of the image.




The photograph is a stacking + stitching of 4x5. Each stacking consists of 66 images, a total of 1320 images. An advance on the Z axis of 0.2 mm. Therefore, the maximum height difference is 13.2 mm.
The overlap between images, in both directions, is 28.6%. The resulting image has 15332 x 12596 pixels, 193.2 Megapixels. It covers a volume of 65.9 x 54.19 x 13.2 mm.

Of the 1320 original images, I have only used about 700 images.
Stacking with Zerene (Pmax). The stitching was done automatically with the PTGUI software. It does not have any subsequent geometric correction. I have not corrected the vignetting or any distortion in camera raw. Only histogram settings and a little detail. The Ptgui scheme:



A crop of the image:



the image:

https://www.easyzoom.com/imageaccess/037cc6c9f96e4db3989cfd97073fd811

I wish you a Merry Christmas .

Best regards.
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Ramón Dolz
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Lou Jost



Joined: 04 Sep 2015
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PostPosted: Mon Dec 24, 2018 10:03 am    Post subject: Reply with quote

Fantastic! Congratulations on putting the lens to such good use. Given the similarity between this lens and the Printing Nikkor 105mm, I imagine the same technique would work just as well on the PN105.
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Lou Jost
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mawyatt



Joined: 22 Aug 2013
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Location: Clearwater

PostPosted: Mon Dec 24, 2018 11:42 am    Post subject: Reply with quote

Ramón,

Superb image!! Your telecentric lens configuration and Stack & Stitck setup is working splendidly Very Happy

Did you use Zerene to measure the scale change for evaluating telecentricity?

When you did your Zerene stacks for use in the image did you keep all alignments OFF or ON?

BTW I found the Mitutoyo 5X with Raynox 150 tube produced a 0.004 ~ 0.008 range during a 6 tile image session (20 micron steps going ~2mm deep), so your 0.0041 is excellent.

Just to clarify 0.0041% is 0.000041, or 0.041 parts per 1000, so think you mean 0.41% or 4.1 parts per 1000. Please correct me if I'm wrong.

Best & Happy Holidays,
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Last edited by mawyatt on Mon Dec 24, 2018 11:52 am; edited 1 time in total
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mawyatt



Joined: 22 Aug 2013
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PostPosted: Mon Dec 24, 2018 11:49 am    Post subject: Reply with quote

Lou Jost wrote:
Fantastic! Congratulations on putting the lens to such good use. Given the similarity between this lens and the Printing Nikkor 105mm, I imagine the same technique would work just as well on the PN105.


Lou,

Do you think the placement of the aperture would be the same for the PN105? If so, where do you think that placement would be on the PN105 setup. Same 40mm from the rear wouldn't be the same optically on the PN105 I would think, and don't have the Nikon 8000 Coolscan lens so cant say for sure.

Best & Happy Holidays,
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dolmadis



Joined: 07 Dec 2011
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PostPosted: Mon Dec 24, 2018 11:56 am    Post subject: Re: Telecentric Scanner-Nikkor ED LENS: Nikon 8000 ED lens Reply with quote

RDolz wrote:
I have made it telecentric with the method of mounting a diaphragm between the lens and the sensor. The diaphragm is about 40 mm from the back of the metal barrel of the lens. The diameter of the diaphragm is approximately 9 mm.



Very useful configuration which by example is well proven.

Would be quite interested in a part inventory from either end if convenient please.

Thanks


John
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Lou Jost



Joined: 04 Sep 2015
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PostPosted: Mon Dec 24, 2018 12:03 pm    Post subject: Reply with quote

Mike, I think this would be a good starting point for the distance to use with the PN105, but we'll need to adjust it. I'd use the standard trick: use a second camera with a fast lens focused at infinity, aiming it through the front element of the PN105, and moving the aperture around until the aperture edge is in focus on the second camera's viewfinder or screen.

The best thing about Ramon's test is that it shows his lens responds well to this new aperture. The PN105 is very similar; I had them both for a while.
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ray_parkhurst



Joined: 20 Nov 2010
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PostPosted: Mon Dec 24, 2018 3:38 pm    Post subject: Reply with quote

How is the aperture calculated for such an arrangement? My first instinct is to do a simple calculation of focal length / physical aperture, which would give f11 nominal or f23.3 at m=1.12. However, the uploaded image looks much cleaner than it should if it were at f23.3, so I am wondering what is the correct method for calculating the aperture...
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rjlittlefield
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PostPosted: Mon Dec 24, 2018 3:45 pm    Post subject: Reply with quote

ray_parkhurst wrote:
How is the aperture calculated for such an arrangement?

Think about what the sensor sees: a 9 mm aperture located roughly 1.12*100mm away from the sensor.

The effective f-number is then 112/9 = f/12.4 .

--Rik
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ray_parkhurst



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PostPosted: Mon Dec 24, 2018 3:53 pm    Post subject: Reply with quote

rjlittlefield wrote:
ray_parkhurst wrote:
How is the aperture calculated for such an arrangement?

Think about what the sensor sees: a 9 mm aperture located roughly 1.12*100mm away from the sensor.

The effective f-number is then 112/9 = f/12.4 .

--Rik


Excellent explanation. Thanks Rik...Ray
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RDolz



Joined: 28 Aug 2017
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Location: Valencia (Spain)

PostPosted: Tue Dec 25, 2018 2:26 am    Post subject: Reply with quote

Hello, sorry I have not answered before ... the Christmas celebration began right after uploading the information to the forum.

Lou, Mike, thank you very much for your words.

I will answer in order:
mawyatt wrote:

Did you use Zerene to measure the scale change for evaluating telecentricity?

When you did your Zerene stacks for use in the image did you keep all alignments OFF or ON?

BTW I found the Mitutoyo 5X with Raynox 150 tube produced a 0.004 ~ 0.008 range during a 6 tile image session (20 micron steps going ~2mm deep), so your 0.0041 is excellent.

Just to clarify 0.0041% is 0.000041, or 0.041 parts per 1000, so think you mean 0.41% or 4.1 parts per 1000. Please correct me if I'm wrong.

Mike, Yes, I use the value of the Zerene scale to measure the telecentricity. The calculation that I do, and if I have not made a mistake, is the following:

In a stacking of 13 images, Zerene gave a total scale change of 0.99465175785037. This means, in my sensor that it has 4896 pixels horizontally, a change of 4896- (4896 * 0.99465175785037) = 2.618 pixels

This change of scale is for the 13 images, therefore, between each image there is a change of scale of 2.618 / 13 = 0.201 pixels, which means a variation between each image of 0.0041%.

And here I am wrong, because I said it was 0.41 parts per thousand, ... but in reality it is 0.041 parts per thousand (I forget that my calculations in excel are in parts per 10000).

The Zerene preferences that I have used in this image are:



Normally I cancel the scale, but the telecentricity measurement was so good, that I tried to activate it ... and it worked perfectly.


dolmadis wrote:

Would be quite interested in a part inventory from either end if convenient please.

John, The setup consists of:
Coolscan 8000 / Adapter Tube For 52mm Leica X1 X2 Camera (modified with screws) / Adapter M52-F42 / extension ring 14mm M42-F42 / Adjustable Focusing Helicoid (12mm - 19mm) F42-F42 / Diaphragm M42-M42 / extension ring 28mm F42 -M42 / extension ring 28mm F42-M42 / Helicoid (25mm-50mm) F.42-M.42 / F.42-FX Mount / FUJIFILM X-T1 body. (M = male, F = female)

Lou Jost wrote:
I'd use the standard trick: use a second camera with a fast lens focused at infinity, aiming it through the front element of the PN105, and moving the aperture around until the aperture edge is in focus on the second camera's viewfinder or screen


The method that Lou says is perfect, but I find it easier to use a small telescope monocular, instead of a camera, to find the distance where the diaphragm should be mounted.

Lou Jost wrote:
Given the similarity between this lens and the Printing Nikkor 105mm, I imagine the same technique would work just as well on the PN105


Lou, Yes, I suppose the setup for the PN105 should be very similar, .. and as you can imagine, maybe with a little better image quality, ... but unfortunately I do not have this lens.


Best & Happy Holidays,
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Ramón Dolz
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Lou Jost



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PostPosted: Tue Dec 25, 2018 8:07 am    Post subject: Reply with quote

Ramon, I've been quantifying telecentricity by measuring the ratio of the scale factors between successive frames, using the step sizes in Rik's Zerene table. This is insensitive to stack depth. And if you do it in different parts of the stack, you can find out if the central region is more telecentric than the margins.

Also, I think each successive scale factor is the previous one multiplied by the current one. So a more meaningful measure of the per-step scale difference would be the Yth root of X, where y is the number of steps and X is the final scale factor. Maybe Rik can tell us if I am right about that.
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mawyatt



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PostPosted: Tue Dec 25, 2018 8:09 am    Post subject: Reply with quote

Ramón,

I see, you have a 0.005348... (1-0.99465...) scale change over the total 13 images, which gives 0.005348.../13 scale variation between each image.

Best & Happy Holidays,
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Lou Jost



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PostPosted: Tue Dec 25, 2018 8:16 am    Post subject: Reply with quote

Mike, see my comment above. I don't think this is the right way to think about scale factors. But let's wait for Rik to chime in since he knows how they are calculated in his program.
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RDolz



Joined: 28 Aug 2017
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PostPosted: Tue Dec 25, 2018 9:20 am    Post subject: Reply with quote

It would be perfect if we had a standardized method to measure the telecentricity of a system.

Lou, as you very well say, the center of the image is more telecentric than on the edges. That is why I assume the measure as "average" since it is the value that Zerene gives for the whole image.

Finally we wait for Rik to explain the calculation of Zerene, or how to use their values to calculate the telecentricity.
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Ramón Dolz
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mawyatt



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PostPosted: Tue Dec 25, 2018 10:18 am    Post subject: Reply with quote

Lou,

I was just trying to understand the method Ramón used, but not sure how Zerene does this calculation either.

The info I gave for the Mitty 5X and Raynox 150 was for the entire stack range, not from image to image. Here's an example of what I'm referring to. Using:

Y = K^X, I get ~ 1.000089 for K




Best & Happy Holidays,
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Last edited by mawyatt on Tue Dec 25, 2018 10:30 am; edited 1 time in total
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