Nikon U10 and U20...

[g4lab]

My apologies for perpetuating the Stolze number fallacy which I got from the two sources you cited. Both have been like bibles to me my entire adult life.

Joseph I MAY have a spare copy of Blaker. I will have to go look. I used to but may have given it to someone.
I let a photographic book dealer really rape me on a copy of Lefkowitz.
But it is in hardback. Usually it is soft cover. It still was too much.
Pre Internet days.

Welcome aboard fluor_doublet.

I have to ask you, what is the apparatus in this photo "syousennkyou4"
At first I thought it might be an advanced piece of audio equipment, when I looked at the small version. Is it some kind of ultrasonic measuring device??

There must be some correction for the hemispheres, not unlike immersion lenses, for the U series of objectives. Wouldn't you think? RI approximately equal to 1.513 compared to air at 1.00003 or whatever the exact values are. This would shorten the apparent working distance.
I believe universal stages are never used without the hemispheres. and on petrographic thin sections. This would imply that U series objectives probably would not be up to their potential in just air.

[Charles Krebs]

Ahhh... finally!

Great information. I've been following this post because I also have these objectives (along with a 3X) and have wondered what they were originally used for. The only thing I had "heard" was that they were used with a "universal stage" but that didn't mean much to me.

Thanks for filling in some blanks.

Do you have any idea of the years of manufacture? I'm curious if they were intended to be used with addition eyepiece chromatic correction (my guess is that they were). Chromatic aberration doesn't seem too bad, but certainly not perfect.

Charlie

[fluor_doublet]

Hi.

>There must be some correction for the hemispheres, not unlike immersion lenses, for the U series of objectives. Wouldn't you think? RI approximately equal to 1.513 compared to air at 1.00003 or whatever the exact values are. This would shorten the apparent working distance.
>I believe universal stages are never used without the hemispheres. and on petrographic thin sections. This would imply that U series objectives probably would not be up to their potential in just air.


Yes. Of course some aberration corrections are important. Especially, spherical and chromatic aberrations are.
However, my set of universal stage contains three kinds of hemispheres, with different RIs and diameters.
So I believe that the objectives are not corrected under hemisphere-sandwiched conditions.
Determination of the orientation of crystal axis is done visually.

The photo "syousennkyou4" is a deceitful metaphysical crystal tester.


>Do you have any idea of the years of manufacture? I'm curious if they were intended to be used with addition eyepiece chromatic correction (my guess is that they were). Chromatic aberration doesn't seem too bad, but certainly not perfect.

I don't know, but maybe mid 1970s to 1980s. Because the universal stage was actively made in that era. The objectives were corrected only achromatically, not apochromatically.

[Joseph S. Wisniewski]

Fluor, thanks.

That tells me what I think I'm going to end up using these things for. If they really are for polarized use, then they should be strain free. And if they're 160mm tube, their long working distances may decrease a little on the 210mm tube Optiphot, but they should still be pretty good. We'll see how well corrected they are at the wrong tube length.

How come everybody has the 5x but me?

[augusthouse]

The Universal Stage aspect of this thread is rather interesting.

Here is another link with reference to a Leitz.

http://www.modernmicroscopy.com/main.as ... =75&page=2

If you have a look in the usual place you will find an Emmons cell for the Leitz universal stage.

I haven't come across a 5x for you yet Joseph.

Craig

[Tonikon]

Hi Joseph and Hello Everyone...
I'm a new member from Italy (sorry for my imperfect English) and I'm very happy to have found this forum.
Yes, I have a Nikon U10 and a Nikon U20 and I use them for High Magnification Photomacrography, without eyepiece and in conjunction with Stacking Software (CZP).
I have deeply tested them with a Leitz SM microscope, modified to accept a Nikon D70s. I have noticed that the U10 has an outstanding resolution and no CA (although not apochromatic), while the U20 has less contrast a a lot af CA at corners.
I have also noticed that their magnification isn't according to 160mm tube length, because U10 seems to be more a 21mm than a 16mm (it gives much less magnification than a Luminar 16, and also mor resolution...). But I have an uncommon sheet (a sort of price list of Nikon petrographic microscopes) that indicates that their tube lenght is 160mm...boh!
I have tested that the Nikon U20 gives better corner resolution using a tube lenght of 200mm or more (stability problems apart...)
I only have a Macro-Nikkor 65/4.5, a Canon 35/2.8, a Milar 50/4.5 and very soon I hope to keep a Luminar 63/4.5.
I'd like to find another 20x that gives better corner performance with the same WD of th U20 (about 15mm!!!), but I'm not yet expert of microscope objectives.
Now, I'll try to attach two pics of my Nikon U10 and U20.
If you desire (Joseph), I can send to you the data sheets that speak about Nikon U lenses.
Ciao

Toni





P.S. How do you calculate focal length and f-stop of microscope objectives?

[rjlittlefield]

Tonikon, welcome aboard!

How do you calculate focal length and f-stop of microscope objectives?

Roughly, the focal length of a microscope objective can be calculated from the basic lens formula. Focal length = focal distance / (magnification+1), where "focal distance" is the distance from the image plane to the rear principal plane of the lens. The problem is that you never know exactly where the rear principal plane of the lens is.

As a rough approximation, you can assume it is in the middle of the glass. You can also assume that the image plane is about 10 mm inside the tube. So, a 10X objective whose glass is 20 mm from its mount, and which is designed to work on a 160 mm tube, would be predicted to have a focal length of about (160-10+20) / (10+1) = 15.5 mm.

In practice, this calculation often underestimates the focal length. Here, Charlie Krebs lists the FL of several 10X 160 mm tube length objectives as 16.92, 18.96, 17.69, 16.9, 18.98, 15.69

The equivalent f-number of an objective is 1/(2*tan(asin(NA))). So, an NA 0.22 objective corresponds to about f/2.2 . (For small NA's, a good approximation is that f-number = 1/(2*NA). At NA=0.22, that would give f/2.3, close enough for all practical purposes.)

If you have in mind comparing objectives to macro lenses, you also need to know that many lenses have "pupillary magnification factors" that give them smaller than marked f-numbers when used on long extensions. For example my Olympus 20 mm f/2.0 bellows lens actually acts more like an f/3 lens when used on 150 mm of extension. So it would be a mistake to believe that lens has a wider aperture than your objective, just because the lens's marked f/2.0 is wider than f/2.2 calculated for the objective. In practical use, the lens has a smaller aperture, f/3 versus f/2.2.

--Rik

[Tonikon]

Tonikon, welcome aboard!

Thank you very much, Rik...this forum for me was an incredible discovery!

Focal length = focal distance / (magnification+1)...

So, for a 160mm tube, my Nikon U10 should be a 15.5mm f/2.2 and for a 210mm tube, it should be a 20mm f/2.2. Testing my real objective, it gives a magnification of 6,7X with 160mm of bellows extension, and this is very strange (magnification too much far from 10x theoretical). Comparing it with a Luminar 16mm f/2.5, the Nikon U10 gives less magnification. So, I suppose that it is about 20mm (or more) of focal lenght.

Thanks and Ciao

[Joseph S. Wisniewski]

Hi Joseph and Hello Everyone...

Hi Toni. Welcome aboard. I saw the thread with the pictures of your setup, and left you a comment about the D70 and Nikon capture that you might find interesting.
Now, I'll try to attach two pics of my Nikon U10 and U20.

If you desire (Joseph), I can send to you the data sheets that speak about Nikon U lenses.

Thank you, Toni, I would be very grateful if you did that.

Joseph

[augusthouse]

There are a couple of U5 Achromat Pol Microscope Objectives on eBay.

270570087665

Quote from listing:

This objective are required with the Universal 4-axis stage (77240) described in the Polarizing Microscope POH-2 catalog. It is strain-free, equipped with iris diaphragm and when used with the hemisphere on the universal stage, has a relatively short working distance. When used on ordinary microscopes, the working distance increases to a marked degree. It is not flat field like other low power planachromats, however it can be used to advantage for transmitted or reflected light microscopy, where extra long working distance is a requirement. The specifications when used without the hemispherical lens are as follows: Product Number 77250, Magnification 3.2X, Numerical Aperture 0.07 and working distance is 18.8mm. When used with the hemispherical lens the numerical aperture increased to 0.10. These objectives have a parfocal mount of 37mm but could be extended with a collar to make the parfocal distance 45mm. This is a 160mm TL objective.

Craig

[Tonikon]

...But the Nikon U5 isn't as good as the Nikon U10. I had a Nikon U5 and for me, it's not advisable for photomicrographic use. For me...

[johan]

Someone just asked me a question related to this - they currently use a U10 and would like to know if there's a higher resolution metallurgical objective with same or greater working distance available, both in 10x and in 20x. Anyone know of such things?

[ChrisR]

U20 WD is 20mm or so - I've just been using one. Hard to beat.

Finites? Do they have to fit a microscope? The MMs are quite good. The 20x is not common though.
I only have 1,2,3,5,10x

Measurescope lenses
1x NA 0.03 WD 79mm
3x NA 0.09 WD 75.5mm
5x NA 0.13 WD 64mm
10x NA 0.2 WD 49.5mm
20x NA .4 WD 20.3mm
50x NA .55 WD 15.1mm
100x NA .75 WD 4.1 mm

There were a couple of SLWDs
I have a couple of those..

[enricosavazzi]

To the best of my knowledge, Nikon microscope objectives U5, U10, and U20 were designed for polarizing microscope equipped with universal stage, to measurement of optical axis orientation of a polycrystalline thin sample.
It might be helpful for you to check the following site;
http://www.olympusmicro.com/primer/anatomy/stage.html
Because of the sample must be sandwiched by two glass hemisphere, this objectives were LWD designed.
[...]

This also agrees with what I know. These objectives are designed for use with the glass hemispheres (which behave as weak lenses because of the spherical surface, in addition to the optical properties of the thick glass). This means they are not used within design parameters in photomacrography of subjects in air. However, they are not fast lenses, so they still perform relatively well even in the latter use.

Unless you can find them very cheap (which is unlikely because of the "Nikon" brand), there are better alternatives at the same prices.

The aperture rings are mostly ornamental on these lenses. They should almost always be used fully open.

[johan]

Thanks gents