1948 AO Spencer Monocular Eyepiece

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J_WISC
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Location: Wisconsin, USA

1948 AO Spencer Monocular Eyepiece

#1 Post by J_WISC » Thu Feb 09, 2023 8:04 pm

Hello.

Regarding the 1948 AO Spencer microscope shown in the photo, I'm curious about the eyepiece. Does someone recognize the style?

1948 AO Spencer Monocular Microscope Eyepiece.jpg
1948 AO Spencer Monocular Microscope Eyepiece.jpg (63.55 KiB) Viewed 2963 times

(I do not own the microscope. I'm just curious.)

Thanks!

dtsh
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Re: 1948 AO Spencer Monocular Eyepiece

#2 Post by dtsh » Thu Feb 09, 2023 10:27 pm

From the image, I would say it's from something else as there appears to be a groove along the edge to allow adjusting in/out while keeping it captured which doesn't at all look like something I would expect to see. On all the AO gear I've handled that sort of adjustment is typically done on one of the eyepiece tubes and would be superfluous on a monocular. It's possible it's just some extra part from who knows what that was placed over the correct eyepiece, I can't tell from the image.

Edit: judging by the objectives, I think the Cat.146 10x and Cat.147 15x would be appropriate choices, plenty of others one could pick too and get a good image.

apochronaut
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Re: 1948 AO Spencer Monocular Eyepiece

#3 Post by apochronaut » Fri Feb 10, 2023 4:22 pm

The 1949 catalogue for the series 15-35-65 and 75 doesn't yet show the 146 and 147 eyepieces but does show the objective series with the 7 colour coded rings that were used right through the 50's to the end of the 160mm era.
Probably the #146 and #147 eyepieces, didn't come along until shortly after. The eyepiece in your microscope is the focusing derivative of the 146, which is cat. # 435.

The microscope in the picture , appears to be a model 33HYZ : one of the 5 models of bacteria count microscopes they sold during that time. Even though the serial# may give it a date of 1948, that was likely the date of mfg. It could have been shipped much later, into the early 50's when the # 435 eyepiece was in production. ....or possibly retrofitted with an up to date optical system giving wider, flatter fields post production.
That base model #33 was discontinued into the early 50's in favour of a similar concept based on series 35 or even 15 frames.

J_WISC
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Location: Wisconsin, USA

Re: 1948 AO Spencer Monocular Eyepiece

#4 Post by J_WISC » Sun Feb 12, 2023 5:10 am

Are the 10x and 43x objectives on the microscope in the photo of value? Are they suitable for a Spencer 5LRH?

apochronaut
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Re: 1948 AO Spencer Monocular Eyepiece

#5 Post by apochronaut » Sun Feb 12, 2023 3:23 pm

Those are not all that much different than the 10X and 44X achromat objectives that preceded them. In use the main difference is slightly flatter fields. If they have a C prefix on the serial #, then they are coated , an advancement in that series of 160mm achromats giving somewhat better contrast. There was also a 4mm .85 N.A. achromat which I have seen the previous 44X chrome barrel version and it is a very good objective but I do not recall seeing one of those with the 7 colour code rings. I'm guessing it is a 43X .66. The 43X .85 from the 50's that I have seen has a smooth chrome barrel and is marked 43X .85 l.w.d., which seems only about the same working distance as the .66 version , so enough to use with a haemocytometer still.
There were never any fully plan AO 160mm achromats
The #5 was slmost always fitted with apochromats

J_WISC
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Location: Wisconsin, USA

Re: 1948 AO Spencer Monocular Eyepiece

#6 Post by J_WISC » Sun Feb 12, 2023 4:03 pm

Thank you dtsh and apochronaut for your help.

I’m tempted to add the microscope in the photo to my collection. But perhaps better to focus on better objectives for the 5LRH?

(My wife wonders when I’ll stop collecting and start actually using microscopes. Right now, I’m enjoying just learning about what is out there. Is this weird?)

apochronaut
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Re: 1948 AO Spencer Monocular Eyepiece

#7 Post by apochronaut » Sun Feb 12, 2023 10:10 pm

I would do the latter. There isn't much intrinsically interesting about the 33HYZ, unless it is in really good shape and really cheap. The principle features that distiguish it as a bacteria count microscope are a focusable eyepiece with reticle and an oil immersion objective. It otherwise is a pretty pedestrian monocular small lab scope
There is a lot if scope(HA!) with the series 5. Since it was discontinued after 1955, some more modern non original parts could be applied to it , extending it's already considerable potential.
While there was not a trinocular head available, a quick change photo monocular with a large diameter optical tube was available. The photo tube's extra diameter avoids the possibility of any internal reflection and light scatter. One thumb screw and the binocular comes off and photo tube and camera on. Thus, it is possibly a camera ready microscope.
The 5 can be set up to achieve an 18mm f.o.v. with compensating eyepieces that arrived via different manufacturers who clung to the 160mm system years after AO had moved on.Although not absolutely perfect the Olympus Bi 10X W.F. work well, bumping the modernity of the instrument forward more thsn s few years.
You are not stuck with AO or Spencer objectives. Any short format 160mm objective will work as long as the noeepiece has only those objectives. The eyepieces might need to be matched but a more recent set of shorty Nikon planfluor for instance might be a more available choice than AO apochromats for instance.
It would be hard to beat the condenser you have.
The low 1 micron fine focus would be hard to beat.
I am unaware what stage yours carries but chances are the stage would be hard to beat.
Just the stability of the brass body alone makes for an impressive potential.

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