Spencer Objective Collection

Everything relating to microscopy hardware: Objectives, eyepieces, lamps and more.
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J_WISC
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Spencer Objective Collection

#1 Post by J_WISC » Tue Mar 14, 2023 1:56 pm

Hello.

Since I've asked a lot of questions about Spencer objectives, here's the entire collection in one place. I appreciate all advice shared earlier in the forum. One of my current goals is ensuring I have an appropriate eyepiece or matched pair of eyepieces for the 50x apochromat.

A: 32mm, 16mm NA 0.25 10x, 4mm NA 0.66 44x
A_32mm_10x_44x_smaller.jpg
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B: 16mm NA 0.25 10x, 4mm NA 0.66 44x
B_10x_44x_smaller.jpg
B_10x_44x_smaller.jpg (140.27 KiB) Viewed 1463 times

C: 40mm 2.8x
C_2.8x_smaller.jpg
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D: 4mm NA 0.95 ~50x apo (magnification based on comparison to other objectives)
D_4mm_apo_smaller.jpg
D_4mm_apo_smaller.jpg (102.41 KiB) Viewed 1463 times

E: 3mm NA 1.15 60x water immersion
E_60x_water_smaller.jpg
E_60x_water_smaller.jpg (105.03 KiB) Viewed 1463 times
Last edited by J_WISC on Tue Mar 14, 2023 4:55 pm, edited 1 time in total.

J_WISC
Posts: 107
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Location: Wisconsin, USA

Re: Spencer Objective Collection

#2 Post by J_WISC » Tue Mar 14, 2023 2:04 pm

I also have three oil immersion objectives. I'm not ready to learn oil immersion microscopy.

The first two are 1.8mm NA 1.25 and 1.30 95x. The last is assumed oil immersion, but not marked oil immersion. It is 2mm NA 1.40 90x apo. My condenser is only NA 1.25, so I don't think using the last two is an option right now, unless it's possible to add an NA 1.30 condenser to a 1916 microscope.


oil_smaller.jpg
oil_smaller.jpg (141.98 KiB) Viewed 1461 times

apochronaut
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Re: Spencer Objective Collection

#3 Post by apochronaut » Tue Mar 14, 2023 4:26 pm

In the 1914 catalogue, Spencer listed 3 condensers. A 1.2 N.A. abbe, a 1.4 N.A. abbe and a 1.3 N.A. achromat aplanat.
By 1917 they had added a 1.4 N.A. achromat aplanat, which is odd because they had yet to catalogue a 1.40 N.A. objective. Is your condenser one that adjusts with a knurled knob under the stage? It might be a sleeve type of condenser, so could be replaced with one of the same sleeve diameter. Spencer used dovetail fork type condensers very early on, so most are not sleeve type.

The list of apochromat objectives in 1914 was unchanged in 1917.
16mm 0.30 , w.d. 2.6mm, real field 1.5mm.
8mm 0.60 , w.d. 1.2mm , real field .75mm
4mm 0.95 with correction collar, w.d. 0.26mm, real field .32mm
3mm 0.95 with correction collar, w.d. 0.16mm, real field .24mm
2mm 1.30 oil immersion, w.d. 0.17mm, real field .16mm
1.5mm oil immersion. w.d. 0.13mm, real field .12mm

They also published a table of magnifications with apochromatic objectives giving extra data such as initial magnification that they did not begin engraving on the barrels until after W.W. I.
The magnifications given are 10X, 20X, 40X, 60X, 82X and 110X. They were likely rounding the magnifications off. The 4mm objective and the 2mm objective both went through several changes in the catalogues. Mostly the 4mm was 44X and then later around 1960, it was 43X. The 2mm went from 82X to 85X, then I think 86X before plateauing at 90X. This was likely due to changes in the glass, most likely the fluorite source, as well as the other optical glasses. Prior to W.W. I Spencer was procuring their optical glass from Jena and Paris. During and after WW I ? They might have had to jump through some hoops.

J_WISC
Posts: 107
Joined: Sun Mar 06, 2022 7:28 pm
Location: Wisconsin, USA

Re: Spencer Objective Collection

#4 Post by J_WISC » Wed Mar 15, 2023 4:15 am

I’ve made a mistake. I actually don’t know the N.A. of the condenser on the 1916 microscope. And I have no idea where I got the number 1.25. There are no markings on the condenser. Maybe from a catalog? Standard accessory?

11E30571-A050-4F31-A3BA-859F8CD399BF.jpeg
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The condenser slides into this … held entirely by friction …

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There is an iris diaphragm above the condenser space, locked open when the condenser is in place. And an iris diaphragm below the condenser. The rack and pinion part moves the lower diaphragm sideways for oblique illumination.

J_WISC
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Re: Spencer Objective Collection

#5 Post by J_WISC » Wed Mar 15, 2023 4:28 am

Actually, I’ve made two mistakes. I DO have an N.A. 1.30 condenser, the one on No. 5 research microscope!

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The top portion screws into the lower portion.

I don’t think either the 1916 microscope or research microscope condenser are suitable for oil. Is this an easy upgrade? I really must choose wisely where to invest. This hobby might be getting serious. My wife and friends tell me I’m a collector.

apochronaut
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Re: Spencer Objective Collection

#6 Post by apochronaut » Wed Mar 15, 2023 10:07 am

Both of your condensers are oil immersion. Fully intact high N.A. dry condensers are a modern invention, 1960's forward and are usually achromat. Any condenser can be used dry with performance loss, especially with lower N.A. objectives and many older Abbe oil immersion ones were designed to be split ; the top oil immersion lens being removed for low magnification wide angle performance using the bottom lens only. That has about a .65 N.A. Some were flip top types.

I think you decided that your microscope was a model 15? For some reason I thought it was a jug handle type but it has a curved arm? If a 15, then the default condenser on that was a 1.4 N.A. oil immersion 3 lens abbe wide angle, according to the 1917 catalogue. The 4 condensers carried forward from then are.

The 1.2 N.A. 2 lens abbe. Early ones might not have been marked but I have seen them marked 1.2 ( at some point later becoming 1.25). That condenser was split for use with low power objectives( likely 10X and under) $7.50 in 1917

The 1.3 N.A. achromat aplanat, like the one on your Spencer # 5. Marked. The field is wide enough for the 1.5mm real field of the 10X apochromat.
The condenser lens section on this one carries an R.M.S. thread, allowing for the use of a reversed objective as a condenser. This is of particular value when using apochromats, thus the apochromat condenser can exactly match the requirements of the objective in N.A., colour correction, and field diameter, conserving more coherent light, improving contrast and resolution. Hence the coarse AND fine condenser focus. Also expensive! There are also cardioid DF condensers with an R.M.S. thread that can be mounted in the top too. Those are a lovely, versatile, top of the line condenser. Getting rare. Dovetail too. $25.00 in 1917

The 1.4 N.A. 3 lens wide angle abbe.not marked. $9.00 in 1917

The 1.4 N.A. aplanat. I have not seen one that I know of but presumably marked. $30.00 in 1917

For stands that had the capacity in weight and function to be research stands, Spencer offered an achromat package and then also an achromat/fluorite hybrid package and apochromat package. Huyghens eyepieces for the former two and compens for the latter. The condenser used was a default condenser usually, capable in both field coverage and N.A. for all circumstances within the packages. Later, when they introduced 60X and 90X 1.4 N.A. apochromat objectives, they also offered a 1.4 N.A. achromat aplanat condenser as an option, dropping the 1.4 aplanat.
I'm pretty sure model making could be practiced within reason but probably at considerable extra cost.

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Re: Spencer Objective Collection

#7 Post by apochronaut » Wed Mar 15, 2023 4:29 pm

Thought you could do a double check on your older condenser , just to be sure. There are two ways. Measure the diameter of the top lens, plano surface. If 9mm, it is the 1.4 N.A. Abbe W.F. Abbe condensers are typically 2 lenses. A collecting and condensing front lens and a further condensing back or top lens.
If you wanted to count lenses to be super sure. It's not a bad idea anyway on an old condenser to split it and clean as many surfaces as you can easily get at. They can get a film over the years.
The modified Abbe type wide field condenser that Spencer used until they switched over to an oil aspheric and dry achromat to replace it has 3 lenses. If you unscrew the top section of the condenser, it will separate it into two lens sections. The front or bottom section will have one large bi-convex lens about 25mm across. Looking at the bottom of the top section you will see another convex surface about 15mm in diameter and above it a very severely curved convex surface of seemingly about 75% of that diameter but it is actually only 9mm, since it is being magnified by the lens in front of it.

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Re: Spencer Objective Collection

#8 Post by zzffnn » Wed Mar 15, 2023 7:46 pm

J_WISC,

I can put that 1.3 N.A. RMS condenser and the 60x (3mm) NA 1.15 water immersion objective to good use, if you don’t want them anymore. I am happy to pay for what you paid for them.

apochronaut,

Are there different versions of that 1.3 NA condenser that do not have RMS thread, or do they all have RMS thread? Thank you.

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Re: Spencer Objective Collection

#9 Post by apochronaut » Wed Mar 15, 2023 9:01 pm

Spencer introduced the dovetail condenser mount in 1924. All of the 1.3 N.A. condensers with a dovetail mount up until those made for the series 15/35 in the later 40's had that feature. When the series 5 was discontinued in 1955, there would have been no more.
I think I have seen a similar set up on a Leitz condenser and Baker must have had one too because there was a Baker R.M.S DF condenser.

Earlier than 1924 there was a period when they separated the condenser and iris in the mount. The condenser could be lifted off via a twist and lock mounting flange. A separate twist and lock plate could be installed in seconds, that carried an R.M.S. thread

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Re: Spencer Objective Collection

#10 Post by zzffnn » Thu Mar 16, 2023 12:27 am

Thank you, apo.

If I find that Spencer RMS condenser without microscope, is there a way to tell if it is the right one (and not a series 15/35 one)? Any identifying feature?

I mainly want to adapt it for other microscopes, such as Nikon S inverted or Nikon Optiphot. If the Spencer RMS condenser is not easy to adapt, I would try to find the Leitz or Baker one eventually.

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Re: Spencer Objective Collection

#11 Post by apochronaut » Thu Mar 16, 2023 1:44 am

It has an R.M.S. thread. Much smaller than the thread on the later 1.3 condensers. I posted about those condensers n the thread about the series 4 about 6 months ago. Have a look.

https://www.microbehunter.com/microscop ... 24&t=17540 Third picture from top. Condenser on the left. Notice how large the optical section is. Much larger than the optical section of the 1.3 condenser John posted a picture of, although the lens pack inside it is the same.. The condenser you are looking for was used almost exclusively on the #7 and 14 research stands up until they were discontinued in the early 30's, then on the #33,3 and 5 research stands from then on until they were discontinued, the last of them in 1955 , the #5. All of the latter 3 stands can be identified by the low fine focus. They are the only horseshoe stands that have that.The 33 is a monocular, you don't see many of them, the 3 is a little smaller, weighing around 18 lbs. and the 5 is huge, weighing around 25 lbs. Most around are #3s.

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