B&L Balplan microscope - newer Flat Field or older planachromat?

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Micro_creatures
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Joined: Wed Jul 24, 2019 3:48 am

B&L Balplan microscope - newer Flat Field or older planachromat?

#1 Post by Micro_creatures » Wed Jul 24, 2019 4:08 am

I came into possession of 2 Balplan microscopes - older one with all planachromatic objectives and newer with 4x and 40x flat field.

I am an avid reader of this forum, and did read all Balplan related topics. Older microscope has indeed older version of planachromatic.

Shall I swap newer Flat Field for older Planachromatic, or it is not a wise move? I am one year new to the microscopes, and did not acquire enough exposure to notice distinct difference between them.

What would you do?

apochronaut
Posts: 2702
Joined: Fri May 15, 2015 12:15 am

Re: B&L Balplan microscope - newer Flat Field or older planachromat?

#2 Post by apochronaut » Wed Jul 24, 2019 12:58 pm

Other way around.
The planachromats seem a marked advancement over the 1960's flat field objectives.

I did some tests a number of years ago and found the colour correction of the planachromats to be so good that in one case at least, outperformed the same magnification flat field fluorite made for the Dynoptic. It's not surprising that they stopped production of the flat field fluorites when the planachromats were released. They did subsequently release a 50X .80 planfluorite oil objective.

The transition from the flat field achromats, which arrived with the Flat Field Dynoptic in the mid-60's to the planachromats seems to have begun around 1973 or 74 or so, maybe a little earlier.

In the earliest catalogue I know of to base a reference on, an early 1975 price list, all of the objective line from 2.5X to 100X show new catalogue numbers, from 31-12-20 to 31-12-26, except the 20X, which is still listed as 31-10-61 and the only one pictured as the older blocky straight sided type. By Dec. 1976 the 20X was listed as 31-12-23 and the picture shows the slimmer profile of the newer objectives, rather than the blocky type with the adjustable outer shroud. The earliest objectives with the new catalogue numbers and barrel formats were still marked flat field and the 2.5X seems never to have been marked otherwise, so there are two different series of flat field achromats distinguished by cat.#, barrel type and performance and as well flat field optics and plan optics out there with the same cat.#, similar or identical barrels and equal performance.

Oddly, everything in all catalogues I have seen are described in general as plano and specifically as planachromats. Even the three flat field apochromats that they catalogued for the Balplan, are described as planapochromats, when in fact the barrels say Flat Field Apochromats.

At some point, they must have stopped using the term flat field in literature. The phase contrast objectives were the last series to be converted from flat field to plan. In the 1975 catalogue, they picture the straight sided shroud type Flat Field phase objectives 31-10-51 to 31-10-54 but in 1976 they picture those in the turned brass barrels, marked planachromat cat. #'s 31-12-40 to 31-12-43. In the text though, both series are called "plano phase contrast".

Micro_creatures
Posts: 2
Joined: Wed Jul 24, 2019 3:48 am

Re: B&L Balplan microscope - newer Flat Field or older planachromat?

#3 Post by Micro_creatures » Wed Jul 24, 2019 5:26 pm

Thank you so much for reply, Apochronaut.

Do I understand correctly, that modern achromat objectives are “flat field” in older B&L models?

I’m attaching pics of both microscopes and lenses - newer on the left, older on the right in all images. (newer and older - is a judgement based on level of visible traces suffered abuse and performance.) there is no model number on the older scope.

Any thoughts/opinions are highly appreciated. Never had experience with B&L, my working scope is Unico IP730.


Any useful parts you see I should keep from the older scope?
As far as objectives - you’d change 4x and 40x to planachromats, correct?

Interesting that seamingly similar objectives, like 100x, are still different in small details.
apochronaut wrote:Other way around.
The planachromats seem a marked advancement over the 1960's flat field objectives.

I did some tests a number of years ago and found the colour correction of the planachromats to be so good that in one case at least, outperformed the same magnification flat field fluorite made for the Dynoptic. It's not surprising that they stopped production of the flat field fluorites when the planachromats were released. They did subsequently release a 50X .80 planfluorite oil objective.

The transition from the flat field achromats, which arrived with the Flat Field Dynoptic in the mid-60's to the planachromats seems to have begun around 1973 or 74 or so, maybe a little earlier.

In the earliest catalogue I know of to base a reference on, an early 1975 price list, all of the objective line from 2.5X to 100X show new catalogue numbers, from 31-12-20 to 31-12-26, except the 20X, which is still listed as 31-10-61 and the only one pictured as the older blocky straight sided type. By Dec. 1976 the 20X was listed as 31-12-23 and the picture shows the slimmer profile of the newer objectives, rather than the blocky type with the adjustable outer shroud. The earliest objectives with the new catalogue numbers and barrel formats were still marked flat field and the 2.5X seems never to have been marked otherwise, so there are two different series of flat field achromats distinguished by cat.#, barrel type and performance and as well flat field optics and plan optics out there with the same cat.#, similar or identical barrels and equal performance.

Oddly, everything in all catalogues I have seen are described in general as plano and specifically as planachromats. Even the three flat field apochromats that they catalogued for the Balplan, are described as planapochromats, when in fact the barrels say Flat Field Apochromats.

At some point, they must have stopped using the term flat field in literature. The phase contrast objectives were the last series to be converted from flat field to plan. In the 1975 catalogue, they picture the straight sided shroud type Flat Field phase objectives 31-10-51 to 31-10-54 but in 1976 they picture those in the turned brass barrels, marked planachromat cat. #'s 31-12-40 to 31-12-43. In the text though, both series are called "plano phase contrast".
Attachments
C9F3E64D-4DD5-4C00-B94C-9994377E4EA2.jpeg
C9F3E64D-4DD5-4C00-B94C-9994377E4EA2.jpeg (282.4 KiB) Viewed 550 times
05270B46-1637-4E2D-B301-C2DCEBCB4294.jpeg
05270B46-1637-4E2D-B301-C2DCEBCB4294.jpeg (273.31 KiB) Viewed 550 times
788788E2-8FA5-4260-87C5-B3E769B5180A.jpeg
788788E2-8FA5-4260-87C5-B3E769B5180A.jpeg (258.78 KiB) Viewed 550 times
21A1A427-F09A-4289-B76E-83C507363E72.jpeg
21A1A427-F09A-4289-B76E-83C507363E72.jpeg (270.72 KiB) Viewed 550 times
3B56E469-943E-4D40-80F0-7CBEAC7FBA53.jpeg
3B56E469-943E-4D40-80F0-7CBEAC7FBA53.jpeg (255.6 KiB) Viewed 550 times

apochronaut
Posts: 2702
Joined: Fri May 15, 2015 12:15 am

Re: B&L Balplan microscope - newer Flat Field or older planachromat?

#4 Post by apochronaut » Wed Jul 24, 2019 7:33 pm

Micro_creatures wrote:Thank you so much for reply, Apochronaut.

Do I understand correctly, that modern achromat objectives are “flat field” in older B&L models?
No. Read again what I wrote. The information relates only to B & L microscopes designed to use objectives marked flat field, planachromat, flat field fluorite, planfluorite or flat field apochromat.

[/quote]I’m attaching pics of both microscopes and lenses - newer on the left, older on the right in all images. (newer and older - is a judgement based on level of visible traces suffered abuse and performance.) there is no model number on the older scope.[/quote]

Just because a microscope is newer, it doesn't mean it is carrying the newest objectives. The oldest objective you have there is the large barreled 40X .65 flat field

[/quote]Any useful parts you see I should keep from the older scope?
As far as objectives - you’d change 4x and 40x to planachromats, correct? [/quote]

Might as well but the flat fields with the large middle grip ring are probably the same optics as the plans


apochronaut wrote:Other way around.
The planachromats seem a marked advancement over the 1960's flat field objectives.

I did some tests a number of years ago and found the colour correction of the planachromats to be so good that in one case at least, outperformed the same magnification flat field fluorite made for the Dynoptic. It's not surprising that they stopped production of the flat field fluorites when the planachromats were released. They did subsequently release a 50X .80 planfluorite oil objective.

The transition from the flat field achromats, which arrived with the Flat Field Dynoptic in the mid-60's to the planachromats seems to have begun around 1973 or 74 or so, maybe a little earlier.

In the earliest catalogue I know of to base a reference on, an early 1975 price list, all of the objective line from 2.5X to 100X show new catalogue numbers, from 31-12-20 to 31-12-26, except the 20X, which is still listed as 31-10-61 and the only one pictured as the older blocky straight sided type. By Dec. 1976 the 20X was listed as 31-12-23 and the picture shows the slimmer profile of the newer objectives, rather than the blocky type with the adjustable outer shroud. The earliest objectives with the new catalogue numbers and barrel formats were still marked flat field and the 2.5X seems never to have been marked otherwise, so there are two different series of flat field achromats distinguished by cat.#, barrel type and performance and as well flat field optics and plan optics out there with the same cat.#, similar or identical barrels and equal performance.

Oddly, everything in all catalogues I have seen are described in general as plano and specifically as planachromats. Even the three flat field apochromats that they catalogued for the Balplan, are described as planapochromats, when in fact the barrels say Flat Field Apochromats.

At some point, they must have stopped using the term flat field in literature. The phase contrast objectives were the last series to be converted from flat field to plan. In the 1975 catalogue, they picture the straight sided shroud type Flat Field phase objectives 31-10-51 to 31-10-54 but in 1976 they picture those in the turned brass barrels, marked planachromat cat. #'s 31-12-40 to 31-12-43. In the text though, both series are called "plano phase contrast".
[/quote]

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