Breaking the baffling B & L Balplan buffalo.

Everything relating to microscopy hardware: Objectives, eyepieces, lamps and more.
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apochronaut
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Re: Breaking the baffling B & L Balplan buffalo.

#61 Post by apochronaut » Fri Jun 12, 2020 2:04 am

Yes, the Balplan uses a single cemented lens group to accomplish the same task. Luckily, those fo not seem to be affected by the same plague, or at least I have not seen one yet.

microb
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Re: Breaking the baffling B & L Balplan buffalo.

#62 Post by microb » Fri Jun 12, 2020 3:35 am

Oh, I thought the pictures of the cloudy doublet was from the first posted pictures of the Balpan. But that is an older model's binocular head with the cloudy doublet. Never mind.

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Re: Breaking the baffling B & L Balplan buffalo.

#63 Post by BramHuntingNematodes » Fri Jun 12, 2020 3:53 am

Yes, but the function of the doublet is the same as that lens in the Balplan, and their position relative to the objective is the same. Who knows but perhaps some day a Balplan will fall into my clutches and I can see if they are truly different or not.

The lens immediately prior the turret opening wouldn't happen to be 7/16ths of an inch or about 11mm would it now?

I did end up buying that listed scope after the seller sent me a very good price. Bob Martin wrote to say he didn't have anything like a lens, and for the prices these medical surplus folks are unloading whole stands I guess I understand why. If this scope is too a dud it at least comes with the high-intensity lamp housing which I am missing, so not nothing.

This whole time I have had the 40x Balplan Planachromat as described earlier. It's a thick, dense lens, spring-loaded and I have been waiting a couple weeks just to look at some human anatomy slides a medical student at U Penn made with it. Not as chunky as the C-cell battery-like flat field lenses, but there is definitely something about that planachromat that is singular, unusual. It looks to be in decent condition, aside from the laughable "Cambridge Instruments" sticker(!) plastered over the impressive B&L case embossing.
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

apochronaut
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Re: Breaking the baffling B & L Balplan buffalo.

#64 Post by apochronaut » Fri Jun 12, 2020 12:31 pm

Does your Dyna microscope head not have two lenses in it, though? Your failed lens is #33 in the exploded diag. , EF lens assy. part # 311959-073. There is another lens above it is there not? #30, CD lens assy. part # 311959-399. It looks to be threaded in from above, or is that part of the zoom mechanism?

The Balplan does it with a sealed assembly. The forward plano lens surface does have the same lateral dimensions as you describe but it is sealed into a housing of roughly 25mm across that appears to be installed and factory collimated into the nosepiece base. There is a recessed hex screw that appears to be there to lock it into place. The forward section of the lens protrudes from it's mount but everything is sealed and the edge surface is blacked. There is no way of removing what is probably the equivalent to your doublet without breaking the seal of the whole assembly. I honestly don't think the Balplan lens can be removed, aside from dropping out the entire sealed mount it sits in. It is likely cemented in.

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Re: Breaking the baffling B & L Balplan buffalo.

#65 Post by MicroBob » Fri Jun 12, 2020 7:42 pm

Hi together,

here is an image of this lens assembly: https://pubs.acs.org/doi/pdf/10.1021/ac60270a765

BTW: I just tbought a Dynazoom, 160mm type, practically unknown in Germany, lets see in what condition it arrives here. :?

Bob

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Re: Breaking the baffling B & L Balplan buffalo.

#66 Post by microb » Tue Jun 30, 2020 7:30 am

apochronaut wrote:
Mon Aug 29, 2016 11:55 pm
Yes, I know they were made in Rochester but for many years I, and I'm sure I'm not the only one, have been truly buffaloed by their objectives. They don't work in any other microscope nor do other microscope objectives work in a Balplan. This isn't too much of a hardship, because in a number of comparative tests I have done with Balplan achromats in a Balplan, against other contemporary achromats in appropriate stands, the Balplan objectives have always done as well or better. I have felt for a long time that B & L was doing something different, that gave their optics in the last 20 years of their production an edge. The colour correction of the last planachromats they produced is better than some fluorites made up until the 1990's.
Hi,

Do you have pictures and measurements for the analyzer slide as shown here: https://lrak.net/secret/Balplan/balplan ... on_13.html (Analyzer Slide, Cat. No. 31-57-86)

Any info would be appreciated -- plus also an idea on how adding the extra thickness of the adapter does not mess up the focus to the camera.

Thanks,
Ted

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Re: Breaking the baffling B & L Balplan buffalo.

#67 Post by apochronaut » Tue Jun 30, 2020 11:48 am

microb wrote:
Tue Jun 30, 2020 7:30 am
apochronaut wrote:
Mon Aug 29, 2016 11:55 pm
Yes, I know they were made in Rochester but for many years I, and I'm sure I'm not the only one, have been truly buffaloed by their objectives. They don't work in any other microscope nor do other microscope objectives work in a Balplan. This isn't too much of a hardship, because in a number of comparative tests I have done with Balplan achromats in a Balplan, against other contemporary achromats in appropriate stands, the Balplan objectives have always done as well or better. I have felt for a long time that B & L was doing something different, that gave their optics in the last 20 years of their production an edge. The colour correction of the last planachromats they produced is better than some fluorites made up until the 1990's.
Hi,

Do you have pictures and measurements for the analyzer slide as shown here: https://lrak.net/secret/Balplan/balplan ... on_13.html (Analyzer Slide, Cat. No. 31-57-86)

Any info would be appreciated -- plus also an idea on how adding the extra thickness of the adapter does not mess up the focus to the camera.

Thanks,
Ted
I don't have one of those. Perhaps Bill Porter does. You have to think of the Balplan as an infinity corrected microscope, even though that is not marked on the objectives or the literature doesn't mention it. It has split objectives, that's all, so I refer to it as a modified infinity corrected system. From the rear focal plane of any of the semi-objective/common telescope lens combinations to the front focal plane of the telan lens the beam is infinity focused, so accessories introduced in that area do not need additional compensation for light path deviation.

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Re: Breaking the baffling B & L Balplan buffalo.

#68 Post by wporter » Tue Jun 30, 2020 9:25 pm

Yes, I have an analyzer slide, 31-57-86, that fits inside the holder-adapter 31-57-92. I got the slide on ebay somewhere, and it came with the pol filter missing (inner opening) but having the clear glass present in the outer opening. I got a replacement pol filter from Edmund (25mm) which drops in right on top of the plain glass. The inner opening is 21.6mm, hard to find or make a good optical-quality replacement for.

The slide is 7.07mm thick aluminum, 117.3mm long, and 31.66mm wide. There are detents on one edge 26.86mm and 55.42mm from one end, which correspond to the centers of the openings. The ends are tapered, just for ease of inserting into the cavity.
pol slide balplan-1024x1024.jpg
pol slide balplan-1024x1024.jpg (92.99 KiB) Viewed 509 times

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Re: Breaking the baffling B & L Balplan buffalo.

#69 Post by microb » Tue Jun 30, 2020 9:59 pm

wporter wrote:
Tue Jun 30, 2020 9:25 pm
Yes, I have an analyzer slide, 31-57-86, that fits inside the holder-adapter 31-57-92. I got the slide on ebay somewhere, and it came with the pol filter missing (inner opening) but having the clear glass present in the outer opening. I got a replacement pol filter from Edmund (25mm) which drops in right on top of the plain glass. The inner opening is 21.6mm, hard to find or make a good optical-quality replacement for.

The slide is 7.07mm thick aluminum, 117.3mm long, and 31.66mm wide. There are detents on one edge 26.86mm and 55.42mm from one end, which correspond to the centers of the openings. The ends are tapered, just for ease of inserting into the cavity.

pol slide balplan-1024x1024.jpg
Awesome! Thanks.

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Re: Breaking the baffling B & L Balplan buffalo.

#70 Post by microb » Wed Jul 01, 2020 12:35 am

wporter wrote:
Tue Jun 30, 2020 9:25 pm
The slide is 7.07mm thick aluminum, 117.3mm long, and 31.66mm wide. There are detents on one edge 26.86mm and 55.42mm from one end, which correspond to the centers of the openings. The ends are tapered, just for ease of inserting into the cavity.
Thanks. If you have more measurements on the optics diameters and the narrowings, please let me know. I'll probably just use 25.4mm and threading, but for the records I'd like to match the original and then do a customized that will have easier commercial sizes plus maybe a 5 degree tilt like the higher end Olympus slides have.
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Re: Breaking the baffling B & L Balplan buffalo.

#71 Post by wporter » Wed Jul 01, 2020 1:46 am

The large opening is 25.45mm, the smaller is 21.68mm. The support lips are 0.54mm thick. The IDs are both 19.27mm (inner edge of the lips). The linear pol filter OD from Edmund (#54-926, $37.00) is 24.86mm (nominally 25mm). It's not their best filter, but adequate.

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Re: Breaking the baffling B & L Balplan buffalo.

#72 Post by apochronaut » Wed Jul 01, 2020 7:57 pm

There was a seller in China who advertised a stat sized number of optical grade glass pol filters. I enquired about a size he did not list and he replied that he would do any size custom for the same price. Any smaller size I presume. I was looking fir 19mm.

I ended up not following up on that. I can look up his info. if you wish? I think they were quite cheap...8.00, up to 25.00 for a 50mm.

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Re: Breaking the baffling B & L Balplan buffalo.

#73 Post by wporter » Wed Jul 01, 2020 9:11 pm

Phil,
Yes, please look it up & post it here. I for one would very much appreciate it (a source for optical grade linear polarizers, since I've replaced several, and Edmund is not cheap.)

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Re: Breaking the baffling B & L Balplan buffalo.

#74 Post by microb » Wed Jul 01, 2020 10:35 pm

wporter wrote:
Wed Jul 01, 2020 1:46 am
The large opening is 25.45mm, the smaller is 21.68mm. The support lips are 0.54mm thick. The IDs are both 19.27mm (inner edge of the lips). The linear pol filter OD from Edmund (#54-926, $37.00) is 24.86mm (nominally 25mm). It's not their best filter, but adequate.
Awesome. Thanks.

I'd be interested in suppliers as well. Because I'm also looking for various sizes including round 2" dia. glass green and pol filters.

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Re: Breaking the baffling B & L Balplan buffalo.

#75 Post by apochronaut » Thu Jul 02, 2020 8:25 pm

wporter wrote:
Wed Jul 01, 2020 9:11 pm
Phil,
Yes, please look it up & post it here. I for one would very much appreciate it (a source for optical grade linear polarizers, since I've replaced several, and Edmund is not cheap.)
This is the guy, I'm pretty sure. https://www.ebay.ca/itm/Optical-Linear- ... SwsAddt8Xu. Lives in Wuhan.

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Re: Breaking the baffling B & L Balplan buffalo.

#76 Post by microb » Mon Jul 06, 2020 8:16 am

I think this 1969 patent describes the B&L Balplan objective lens assembly: https://patentimages.storage.googleapis ... 481665.pdf

The objective lenses and the tube lens are given in tables.

"Semi-objectives Magnification:* Focal length (mm.)
4X ------------------------------------ 16.5
10X ----------------------------------- 15.8
40X ----------------------------------- 6.9
100X ---------------------------------- 3.3 * When combined with the field corrector lens. "

" Lens 21 [the tube lens] is composed of a double convex lens element designated X which lies in contact along its rear surface with a double concave lens element designated XI. The focal lengths Fx and -Fxr relating to the lens elements X and
XI respectively have values as given in the mathematical statements herebelow wherein the minus (-) sign de notes negative focal length.
0.088DCF (0.108D
0.053D.<-FC0.065D
Ideally, the values for FK and -F should be substantially .098D and -0.059D respectively. The corresponding values of axial thicknesses to and tail for elements X and XI respectively are stated in the following mathematical expressions.
0.012DCt.<0.015D
0.007D.Ct.<0.009D
Ideally, the values of to and t are substantially 0.013D and 0.008D respectively.
Furthermore, lens elements X and XI are made of glass having the following specification of values for refractive index no and Abbé number v.
Absolute values:
1.746<n(X) <1.756
1.608<n(XI) <1.618
22.0<v(X) <32.0
40.0<v(XI) <50.0
Ideally,
n(X) = 1.751 and v(X)=27.8 and
n(XI) = 1.613 and v(XI)=44.2"
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Re: Breaking the baffling B & L Balplan buffalo.

#79 Post by microb » Mon Jul 06, 2020 8:54 am

See column 2 of patent: https://patentimages.storage.googleapis ... 481665.pdf

"Generally speaking, the inventive concept here disclosed is intended to provide a high performance optical system for a plural-objective microscope and particularly the
objective lens system, the outstanding improvement being:
(1) Flattening of the field of the objective lens system.
(2) Balancing of lateral color.
(3) Correction of astigmatism,
(4) Correction of spherical aberration and coma.

Improvement in flatness of field is obtained principally by changes in the usual first order parameters of the objective system. Said changes include:
(a) An increase in the focal lengths of the higher powered semi-objectives and a consequent reduction in the under
corrected Petzval sum of these semi-objectives.
(b) Working the semi-objectives at substantially reduced
magnifications relative to the magnifications of objectives of comparable numerical aperture in standard objective series.
(c) Working the semi-objectives within a substantially reduced object-to-image distance relative to that within which standard series objectives work,
(d) Introducing a fixed position negative corrector lens, designed to work successively as an integral optical component with each semi-objective of the series, said corrector lens working at a magnification such that the product of semi-objective magnification times corrector lens magnification is equal to the magnification of standard objectives of comparable numerical aperture, and introducing Petzval sum and astigmatism contributions which aid in the correction of the field of each semi-objective.

The new series of microscope objectives 22 are designed for image magnifications of 4.0.x, 10.0X, 40.0X and 100.0X in progressive steps, and the individual semi-objectives 14, 15, 16, 17 are correspondingly designed for image magnifications of 0.8.x, 2.0X, 10.0X, and 20.0X per se."

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Re: Breaking the baffling B & L Balplan buffalo.

#80 Post by apochronaut » Mon Jul 06, 2020 12:04 pm

Yes. If you follow through the citations and references, there were a whole slew of patents by Bausch & Lomb and American Optical obviated by the idea of separating the objective section of the microscope from the ocular section.
Microscopes inherently had previously forced the operator to hover over the objective. In the mid-40's ideas became focused on making the ocular section more independent, or rather more remote. The ocular section would receive an image from the objective but it was situated in a more ergonomic location and whatsmore, it could be rotated around the optical axis. There was an almost periscope like idea about viewing through the microscope. This necessitated more optical components between the objective and the eyepiece. Separating the objective I see as a natural outgrowth of accepting the fact that a microscope need not just be an objective magnified by an eyepiece.
I have yet to find any reference in the Bausch & Lomb patents I have looked at to the American Optical design for the series 4, with it's compensating telescope lens. That concept may not have been patentable but the extension of the concept to using a correcting convergent telescope lens was by 1961. Bausch & Lomb kind of stood the concept on it's head somewhat by reversing the beam sequence from convergent to parallel and back again. It may initially have been a way around AO's patent but the idea to utilize the initial convergent beam as a method by which to extend the objective's parfocal length and thus extend the potential for corrections within the objective complex , was pretty savvy. It's hard to not look at the optical quality of the results and not marvel at how good they were in their day.

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Re: Breaking the baffling B & L Balplan buffalo.

#81 Post by BramHuntingNematodes » Mon Jul 06, 2020 3:20 pm

Hmm maybe I can manufacture a replacement doublet after all if these specifications held true in production.
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

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Re: Breaking the baffling B & L Balplan buffalo.

#82 Post by BramHuntingNematodes » Mon Jul 06, 2020 6:38 pm

BramHuntingNematodes wrote:
Mon Jul 06, 2020 3:20 pm
Hmm maybe I can manufacture a replacement doublet after all if these specifications held true in production.
Requires some relatively specific dense crown and dense flint glass lenses, the double concave of which has a somewhat unusual focal length for the 7/16ths diameter. Might require some specific lens grinding apparatus or maybe some math to make an equivalent doublet.
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

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Re: Breaking the baffling B & L Balplan buffalo.

#83 Post by microb » Tue Jul 07, 2020 12:21 am

BramHuntingNematodes wrote:
Mon Jul 06, 2020 3:20 pm
Hmm maybe I can manufacture a replacement doublet after all if these specifications held true in production.
Where do you see the description of the doublet in the nose/objective-turret?

[oops, I used the wrong patent number 3,565,512. It should have read 3428389 https://patentimages.storage.googleapis ... 428389.pdf so I'm editing this below:]
Lens 21 in US3428389 I thought was the corrective lens in the binocular head (https://patentimages.storage.googleapis ... 428389.pdf). I'm not finding a lens spec for the nose piece lens.
Last edited by microb on Tue Jul 07, 2020 7:46 am, edited 1 time in total.

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Re: Breaking the baffling B & L Balplan buffalo.

#84 Post by apochronaut » Tue Jul 07, 2020 3:29 am

It is item 21 but in figure 2 of the 481665 patent. The specifications are from line 30 on page 4 to the middle of page 5.
I don't think the doublet would involve a crown glass element. Both n's are high, with fairly low abbe #'s.
According to charts, the double convex element would be something like a Barium Titanate glass and the double concave element something like a Barium dense flint.
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Re: Breaking the baffling B & L Balplan buffalo.

#85 Post by BramHuntingNematodes » Tue Jul 07, 2020 3:32 am

The doublet has to be assembly 21 if it is immediately in front of the objectives. It's the shared fixed position negative corrector lens.

I have seen some "dense crown" glass with specs close to one of the elements, but only within the ranges and not at the ideal. In any case, at least one of those glass specs I had trouble finding an off the shelf replacement for.
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

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Re: Breaking the baffling B & L Balplan buffalo.

#86 Post by BramHuntingNematodes » Tue Jul 07, 2020 3:38 am

BramHuntingNematodes wrote:
Tue Jul 07, 2020 3:32 am
The doublet has to be assembly 21 if it is immediately in front of the objectives. It's the shared fixed position negative corrector lens.

I have seen some "dense crown" glass with specs close to one of the elements, but only within the ranges and not at the ideal. In any case, at least one of those glass specs I had trouble finding an off the shelf replacement for.
Suffice to say this is not an item which I can spend $10 at the surplus shed for some spare lenses and glue them together.
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

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Re: Breaking the baffling B & L Balplan buffalo.

#87 Post by Scarodactyl » Tue Jul 07, 2020 3:41 am

What is the overall focal lebgth of the lens? It might be interesting to experiment with a normal achromat to get a sense of how vital corrections are--not volunteering to do it myself though, not right now anyway.

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Re: Breaking the baffling B & L Balplan buffalo.

#88 Post by BramHuntingNematodes » Tue Jul 07, 2020 3:46 am

I somehow figured length D to be about 187.8mm which puts the overall focal length of the thing at -33.24mm.
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Re: Breaking the baffling B & L Balplan buffalo.

#89 Post by apochronaut » Tue Jul 07, 2020 3:54 am

Scarodactyl wrote:
Tue Jul 07, 2020 3:41 am
What is the overall focal lebgth of the lens? It might be interesting to experiment with a normal achromat to get a sense of how vital corrections are--not volunteering to do it myself though, not right now anyway.
I think someone tried that a while ago.
Last edited by apochronaut on Tue Jul 07, 2020 4:04 am, edited 1 time in total.

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Re: Breaking the baffling B & L Balplan buffalo.

#90 Post by apochronaut » Tue Jul 07, 2020 4:03 am

Scarodactyl wrote:
Tue Jul 07, 2020 3:41 am
What is the overall focal lebgth of the lens? It might be interesting to experiment with a normal achromat to get a sense of how vital corrections are--not volunteering to do it myself though, not right now anyway.
It's the back lens group of all of the objectives, applies 5X magnification to them all and one of the elements in the doublet has a refractive index of 1.7+.

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