New member with old A.O. Spencer questions

Everything relating to microscopy hardware: Objectives, eyepieces, lamps and more.
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Terry Mc
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Joined: Mon Jun 15, 2020 11:16 pm

New member with old A.O. Spencer questions

#1 Post by Terry Mc » Mon Jun 15, 2020 11:44 pm

Hello all,

Imagine my delight when I came across this fine forum!

I have this A.O. Spencer B-35-83 that dates from 1956, I believe (pic below).

I have some questions regarding the optics for you A.O. wizards!

It has a 4-hole turret, but only has two objectives at this time....a 10X and a 43x. These are achromats.
The eyepieces are the 10X Widefields of the day.

I'd like some advice regarding upgrading the optics....somewhat on-the-cheap. The original optics are clean and seem to work-to-spec.
However, as you would guess there's a decent amount of C.A. and I can't help but to feel that upgraded optics would be sharper, with less false color.

What would constitute upgraded optics that could be purchased used....in order to bring this 'scope up a few notches?

1) Are the objective threads a standard or is there a risk when buying used Olympus, Nikon, etc that the threads won't match (I know that I cannot use infinity objectives, only 160mm ones).
2) Are the eyepieces a standard size, or is there a similar risk when buying used Olympus, Nikon, etc?
3) Would the new, affordable Chinese Plan objectives be an improvement?

Many thanks x 1000 for any learned advice,
Terry

Image

MicroBob
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Re: New member with old A.O. Spencer questions

#2 Post by MicroBob » Tue Jun 16, 2020 6:28 am

Hi Terry,
of cause there are more advanced objectives and eyepieces available that would fit you microscope. But the original achromats should already offer a quite good image. They are not planar, so if you would take pictures through one of the eyepiece tubes they would not be sharp towards the border. And achromats are not perfectly color corrected so on contrasty objects you will see slight colour fringes towards the border of the immage. For many objects and visual observation you objective will do very well.
The chromatic errors you see might have other reasons - are you sure you have set up the microscope right?

Bob

BramHuntingNematodes
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Re: New member with old A.O. Spencer questions

#3 Post by BramHuntingNematodes » Tue Jun 16, 2020 12:36 pm

It's a good looking scope you have there those old so Spencer lenses are fine lenses you'll want to keep them but what do you have going on as far as your light source and condenser
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

dtsh
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Re: New member with old A.O. Spencer questions

#4 Post by dtsh » Tue Jun 16, 2020 2:01 pm

By the age I am guessing the objectives are likely DIN 160, but that's a guess. Any markings on the objective barrels you can share?

Terry Mc
Posts: 38
Joined: Mon Jun 15, 2020 11:16 pm

Re: New member with old A.O. Spencer questions

#5 Post by Terry Mc » Tue Jun 16, 2020 3:32 pm

Many thanks to all!

I do not have the scope by me at the moment, but I can say that the 10x and 43x objectives are AO achromats.
The condenser is also AO and is likely stock. Has iris, no filter holder. Looks like it was originally fitted with a light?
My light is a modest box light with blue filter. I'll want a better one!

Im coming from the telescope world, and as you may know there's a plethora of advanced eyepieces/objectives for them, and so I may be a bit spoiled.
The view through this microscope is "ok". It's not razor-sharp...it's "ok" and the color correction isn't very great....classic achromat performance.

Im curious about better finite objectives, plan/achromat (can't afford apos!), and better eyepieces.
I'm guessing that these old AO WF eyepieces are so-so Kellner design. The lenses don't appear to be coated.

Are the objective threads universal size?

MicroBob
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Re: New member with old A.O. Spencer questions

#6 Post by MicroBob » Tue Jun 16, 2020 3:53 pm

Hi Terry,
to get a good image in the microscope the lighting has to be right and the sample has to be prepared properly. Both are things that are uncommon to the astronomer. To really see what the microscope can do you have to set the condenser properly and use a suitable light source. The object has to consist of slide, very thin specimen, some kind of medium around the object (in rare cases just air) and a cover slip of about 0,17mm. When your object is thicker than about 0,1mm it will become increasingly difficult to gat a good image.

This will be a microscope with finite tube length like 160mm. The objectives have probaly RMS thread. While this sounds well standardized it isn't! :lol: Depending on the brand, age and strenght of the objective different eyepieces fit best. In such an old instrument they probably used non correcting eyepieces for the low power objectives and correction eyepieces for the stronger ones. And these corrections are matched to the objective. So to add other components one has to know a lot and to experiment. I would suggest to first find out whether it is RMS and 160mm and then report back.

Bob

BramHuntingNematodes
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Re: New member with old A.O. Spencer questions

#7 Post by BramHuntingNematodes » Tue Jun 16, 2020 4:57 pm

If the scope is the fixed tube length version, AO did make some Apo lenses for it. They are less common in the secondary market than B&L lenses, but if you can find them they are supposedly top notch (with the corresponding eyepieces). I don't think there were infinity tube apos or any AO plan apos. Reichert made two I think that would work? Anyway, the benefit from these objectives, and I speak from experience with B&L achromats, flourites and apos, is negligible to none at all without a very carefully set up substage and a good condenser. I used a Wild aplanat for a while and now a B&L achromat. The step up from Abbe to aplanat condenser was very noticeable (the achromat not as much but then I don't use the 90x lens often), and AO has made some nice aspheric condensers which should accomplish a similar task for not too much money. You can then use the bottom lens of your Abbe as a field lens in your lighting. You could also do like I did and get an aspheric condenser lens from Thorlabs to use as your field lens, some even come with the back ground for diffusion. With all that, you may be surprised at how well the achromats work.
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

BramHuntingNematodes
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Re: New member with old A.O. Spencer questions

#8 Post by BramHuntingNematodes » Tue Jun 16, 2020 5:07 pm

Also, there is this guy on the boards here who may have completely definitive info for your scope might want to wait for that!
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

Terry Mc
Posts: 38
Joined: Mon Jun 15, 2020 11:16 pm

Re: New member with old A.O. Spencer questions

#9 Post by Terry Mc » Tue Jun 16, 2020 8:12 pm

Thanks everyone!!!!!!!!

Ive been into microscopy on/off since around 1968, so I do know the bare basics. Not so much about the optics though, as you can see.
I do plan on forging ahead to supplement my astronomy hobby, there are soooo many cloudy nights!!!! And, I have a delightful pond in my yard.

I am taking a serious look at a used Olympus today however. I am indeed fond of the AO though! If I get an Olympus Ill donate the AO to my boy's school, they can use it.

apochronaut
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Re: New member with old A.O. Spencer questions

#10 Post by apochronaut » Tue Jun 16, 2020 9:52 pm

The microscope you have is a last of it's kind at AO. They had already moved on to the development of a wide field system with pretty uniform corrections across a 19mm field , with quite close to plan performance while using those standard achromats that you have. They were for sure if not into the development , but on the cusp of developing their first infinity corrected system, so interest in taking 160mm tube systems any further had waned at AO. The series 35 had it's heyday about 1950. If the objectives are coated, they were the last development in 160mm tube objectives at AO. Those eyepieces are a bit antiquated, coming out of development ,just prior to the war and although W.F., they lack the peripheral corrections and planarity that the cat. # 146 10X W.F. have. Those would have been the W.F. choice in 1956. Many instruments such as yours were sold as basic instruments with 10X huygens oculars. It is likely that someone chanced on those W.F. types later and stuck them in. Most microscope eyepiece designs are not directly related to the designs known in astronomy. They are proprietary mostly, designed to over compensate or undercompensate for each objective family's unique aberrations. Usually you can't just adopt the use of a Plossl for instance, like you can with a telescope, although Huygens and to a small degree Kellners were used with common achromats. Your eyepieces were originally designed with a slightly different set of objectives in mind too, so some of the ca you are getting is probably a result of a mis-match.

Many companies were using fairly small objectives up until even the 80's, with what is known as a parfocal length of xx mm. 33,34,35.5,36 and 37 were common and there was a more or less D.I.N. standard of 45mm. Modern Chinese achromats and most other achromats made after about 1980 are 45mm. I haven't tried but I think they may be too long for the focus track on your scope....maybe not. However, several companies; Nikon, Olympus, Kyowa and a couple of others from Japan continued to develop short parfocal optical systems until about 1980, so planachromats from those companies probably could be found that wouldn't stretch the budget too much. You would likely need to purchase the correct eyepieces too.

Another option would be to keep your eyes peeled for higher N.A. achromats, fluorites or apochromats from either AO or B & L. The short barrel parfocal versions don't have much of a market anymore and when they show up, they are pretty inexpensive usually. You should be able to put a set of 4 together for under 200.00 or roughly the same amount as a set of plan Olympus or Nikon short barrel achromats. For some reason B & L apochromats are more widely represented on the ùsed market. While you can mix them, there are slight differences in the degree of under compensation between the two, so if you say had a pair of B & L apos and two other Spencer(AO), you would probably be best to have a set of compens eyepieces for each. There is maybe 1.7mm difference in the parfocal length, not so much that you couldn't take up the difference with shimming.

Always remember. A microscope is 4 telescopes on one mount, all using the same eyepiece.

Terry Mc
Posts: 38
Joined: Mon Jun 15, 2020 11:16 pm

Re: New member with old A.O. Spencer questions

#11 Post by Terry Mc » Tue Jun 16, 2020 11:18 pm

apochronaut wrote:
Tue Jun 16, 2020 9:52 pm
The microscope you have is a last of it's kind at AO. They had already moved on to the development of a wide field system with pretty uniform corrections across a 19mm field , with quite close to plan performance while using those standard achromats that you have. They were for sure if not into the development , but on the cusp of developing their first infinity corrected system, so interest in taking 160mm tube systems any further had waned at AO. The series 35 had it's heyday about 1950. If the objectives are coated, they were the last development in 160mm tube objectives at AO. Those eyepieces are a bit antiquated, coming out of development ,just prior to the war and although W.F., they lack the peripheral corrections and planarity that the cat. # 146 10X W.F. have. Those would have been the W.F. choice in 1956. Many instruments such as yours were sold as basic instruments with 10X huygens oculars. It is likely that someone chanced on those W.F. types later and stuck them in. Most microscope eyepiece designs are not directly related to the designs known in astronomy. They are proprietary mostly, designed to over compensate or undercompensate for each objective family's unique aberrations. Usually you can't just adopt the use of a Plossl for instance, like you can with a telescope, although Huygens and to a small degree Kellners were used with common achromats. Your eyepieces were originally designed with a slightly different set of objectives in mind too, so some of the ca you are getting is probably a result of a mis-match.

Many companies were using fairly small objectives up until even the 80's, with what is known as a parfocal length of xx mm. 33,34,35.5,36 and 37 were common and there was a more or less D.I.N. standard of 45mm. Modern Chinese achromats and most other achromats made after about 1980 are 45mm. I haven't tried but I think they may be too long for the focus track on your scope....maybe not. However, several companies; Nikon, Olympus, Kyowa and a couple of others from Japan continued to develop short parfocal optical systems until about 1980, so planachromats from those companies probably could be found that wouldn't stretch the budget too much. You would likely need to purchase the correct eyepieces too.

Another option would be to keep your eyes peeled for higher N.A. achromats, fluorites or apochromats from either AO or B & L. The short barrel parfocal versions don't have much of a market anymore and when they show up, they are pretty inexpensive usually. You should be able to put a set of 4 together for under 200.00 or roughly the same amount as a set of plan Olympus or Nikon short barrel achromats. For some reason B & L apochromats are more widely represented on the ùsed market. While you can mix them, there are slight differences in the degree of under compensation between the two, so if you say had a pair of B & L apos and two other Spencer(AO), you would probably be best to have a set of compens eyepieces for each. There is maybe 1.7mm difference in the parfocal length, not so much that you couldn't take up the difference with shimming.

Always remember. A microscope is 4 telescopes on one mount, all using the same eyepiece.
What an outstanding post (I appreciate all of them!) !!
Thank you so very much. As a history buff, I could see getting into historical microscopes/collecting. Fascinating! I'd certainly keep the AO if my son's school didn't need an additional scope.

I'll have to look to see what the cat# of my WF eyepieces are. AND, I should post the markings on my objectives; with that info I suppose that you could tell me about mismatched optics. That makes perfect sense!

I'm almost ready to make a move on a local hospital's surplus mid-80's higher-end Olympus. I'll be seeing it later this week. It's a bit of a fixer-upper (alarm bells!) but if the glass is clean (underneath the dust) I'll buy it.

The cool thing about it being that it's modular and disassembles rather easily (the owner's manual details all of that), and I must admit that I am very handy with such things (including restoration of finishes of various types) and so the restoration would be part of the fun. If the objectives restore well, the resale value of them alone would exceed what I'd be paying for the entire scope.

But I'm buying on reputation alone.

apochronaut
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Re: New member with old A.O. Spencer questions

#12 Post by apochronaut » Wed Jun 17, 2020 12:41 am

Your eyepieces are # 135. They just have 10X W.F. stamped on the barrel. When sold as a factory matched pair they also will have an identical serial # marked on each chrome barrel. The # 146 look more like a contemporary eyepiece with a larger cylindrical eyelens section.

Terry Mc
Posts: 38
Joined: Mon Jun 15, 2020 11:16 pm

Re: New member with old A.O. Spencer questions

#13 Post by Terry Mc » Wed Jun 17, 2020 11:40 pm

apochronaut wrote:
Wed Jun 17, 2020 12:41 am
Your eyepieces are # 135. They just have 10X W.F. stamped on the barrel. When sold as a factory matched pair they also will have an identical serial # marked on each chrome barrel. The # 146 look more like a contemporary eyepiece with a larger cylindrical eyelens section.
You nailed it! My WF eyepieces have matching serial numbers.

Are my AO eyepieces of a standard diameter...meaning...can I confidently try other eyepieces from Nikon, etc knowing that they will fit (aside from optical concerns)?

apochronaut
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Re: New member with old A.O. Spencer questions

#14 Post by apochronaut » Thu Jun 18, 2020 1:01 am

The eyepiece tubes are the very standard 23.2mm. Only a few hobby microscopes use a smaller size and some professional models use 30mm in order to increase the field of view beyond the current common default wide field of 20mm.

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