Leitz 80x 1.30 Petrographic objective

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viktor j nilsson
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Leitz 80x 1.30 Petrographic objective

#1 Post by viktor j nilsson » Mon Feb 17, 2020 9:04 am

This funny little objective popped up in my eBay searches:

https://www.ebay.com/itm/164084835993

Image

It's an extremely short-nosed little Leitz 80x Fl (Fluorite?) oil objective with a 1.30 NA intended for a 215mm tube length and no cover slip.
It is marked P (Strain-free polarizing?) and A (no idea what that means).

What is the intended use for this objective? And why on earth is it so short? Is anyone using this type of objective these days?

I am asking as I know I have this exact same lens tucked away in a drawer somewhere, and I've never figured out what it is meant for.

jb89
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Re: Leitz 80x 1.30 Petrographic objective

#2 Post by jb89 » Mon Feb 17, 2020 9:39 am

viktor,

I am not very sure but I think those very short objectives were put into centering rings or clutches and were used on very early 1900's leitz petrographic/metallurgic microscopes.

I want to say I read that they were called "MOP" microscopes but I couldn't find any info in manuals to verify that particular objective

hopefully other board members will be able to tell you for sure

viktor j nilsson
Posts: 273
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Re: Leitz 80x 1.30 Petrographic objective

#3 Post by viktor j nilsson » Mon Feb 17, 2020 11:24 am

Thanks for your input!

With your helpful nudge, I actually think that I managed to find it myself. I think this objective was made for the Leitz Panphot polarizing microscope. Here's the scanned manual:

http://www.science-info.net/docs/leitz/Panphot-6-57.pdf

On Page 13, it lists a Coated fluorite oil immersion (P) 80/1 .30 (P1/10Fl) among the objectives to be used with the "Large vertical illuminator on detachable bracket".

And on Page 14 it gives details for "Objectives for work in incident polarized light (free from strain, for tube length 215mm. and object without cover glass)".
In the table, the "P" on the 80x 1.30 Oel is described as meaning the type of eyepieces best suited for this objective, with P = Periplanatic.

So I guess the explanation for the ultra-short objective is to provide space for both the epi-illuminator, and large rock samples?
Last edited by viktor j nilsson on Mon Feb 17, 2020 11:50 am, edited 1 time in total.

viktor j nilsson
Posts: 273
Joined: Thu Aug 23, 2018 10:12 pm
Location: Lund, Sweden

Re: Leitz 80x 1.30 Petrographic objective

#4 Post by viktor j nilsson » Mon Feb 17, 2020 11:45 am

Also described on P60 in the more detailed instruction book, scanned here:
http://www.microscopy-uk.org.uk/mag/art ... n-book.pdf

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Dmi3n
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Re: Leitz 80x 1.30 Petrographic objective

#5 Post by Dmi3n » Mon Feb 17, 2020 12:12 pm

viktor j nilsson wrote:
Mon Feb 17, 2020 11:24 am

So I guess the explanation for the ultra-short objective is to provide space for both the epi-illuminator, and large rock samples?
Yes, you are right, this "pancake" design was developed to save vertical space for massive illuminator and sample.
Scopes: CZJ NfPk w/ 45mm apo objectives, Phv phase contrast, Epi Pol illuminator, trinocular head, CZJ Epityp-2 Pol (currently dismantled for full restoration and recollimation) w/ D32 microhardness tester and photomicrography attachment.

apochronaut
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Re: Leitz 80x 1.30 Petrographic objective

#6 Post by apochronaut » Mon Feb 17, 2020 4:28 pm

Dmi3n wrote:
Mon Feb 17, 2020 12:12 pm
viktor j nilsson wrote:
Mon Feb 17, 2020 11:24 am

So I guess the explanation for the ultra-short objective is to provide space for both the epi-illuminator, and large rock samples?
Yes, you are right, this "pancake" design was developed to save vertical space for massive illuminator and sample.

This is an immersion objective. There can be no saving of space between it and the sample. These are called short mount objectives and they were used on incident illuminated microscopes made by most companies, in order to remove the space taken up by the upper non optical section of the objective barrel, so it could be included into the incident illuminator section of the optical tube. This kept the height of the instrument down somewhat. Some other designs did not use short mounts and the tubes in those models were lengthened proportionately to around 250mm.
For average incident lit work, they could be threaded in singly or into a nosepiece but for POl work, they needed to be centered very accurately. Nosepieces with centering adjustments were not in use until fairly recently so in order to save the time of adjusting the centering of each objective as they were used, each objective was threaded into a stirrup mount that had a precision fit to a specialized objective holder. The objectives were precentered, then clipped into the nosepiece, maintaining precise alignment.

The other reason a short mount was preferable was that in the process of centering and then removing and replacing objectives, a short barrel would be more likely to to maintain alignment, since those with a longer barrel would exaggerate any variance or potential play at the mount.

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Dmi3n
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Re: Leitz 80x 1.30 Petrographic objective

#7 Post by Dmi3n » Mon Feb 17, 2020 6:41 pm

apochronaut wrote:
Mon Feb 17, 2020 4:28 pm
Dmi3n wrote:
Mon Feb 17, 2020 12:12 pm
viktor j nilsson wrote:
Mon Feb 17, 2020 11:24 am

So I guess the explanation for the ultra-short objective is to provide space for both the epi-illuminator, and large rock samples?
Yes, you are right, this "pancake" design was developed to save vertical space for massive illuminator and sample.

This is an immersion objective. There can be no saving of space between it and the sample.
Of course I meant the space between the stage and illuminator coupling, not the parfocal length or working distance of the objective.
Scopes: CZJ NfPk w/ 45mm apo objectives, Phv phase contrast, Epi Pol illuminator, trinocular head, CZJ Epityp-2 Pol (currently dismantled for full restoration and recollimation) w/ D32 microhardness tester and photomicrography attachment.

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