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Vintage Olympus CH microscope vs modern Olympus microscopes?

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#1 db2005

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Posted 25 October 2019 - 12:24 AM

This is my first new topic in the Cloudy Days & Microscopes forum.

 

However, I have spent a lot of time since my early teens playing with microscopes and observing the microcosms in prepared slides and drops of water. I have also used microscopes to introduce young people and other budding scientists to the wonders of microscopy.

 

For quite some years I have owned a second (third?, fourth?) hand Olympus CH microscope for several years which I have used exclusively for hobbyist purposes. It was handed down to me from my grandfather who AFAIK purchased it from a an acquaintance who got it from a liquidated veterinary practice. This microscope it is clearly in a different optical league than my other microscopes, but its age is clearly showing: spare parts are hard to come by, the tungsten halogen light source gives an unnatural color to specimens and is causing wet samples to dry up and kills the objects I'm observing unless I'm very careful. I did made an improvised dark-field disc for it which works reasonably well but I would like to use dark-field more properly. A couple of years ago I was able to get a quick peek through a high-end Olympus optical microscope (I don't recall the exact model, but it was something in the 10,000 $ class) in an optical lab, and I was like "oh, wow... I didn't know optical microscopes could be that good".

 

Since my CH microscope is now probably 40 years old I was wondering if anyone can tell me if newer-generation microscopes like the Olympus CX23 or CX33 series would offer real advantages over my CH microscope. I'm speaking mainly of optical quality, but also eye relief and upgradeability. I am normally wearing eyeglasses compensating for astigmatism but the eye relief on my CH microscope's eyepieces is too tight for that. Is eye relief generally better on modern microscopes or are long-eye relief eyepieces something I need to purchase as an upgrade? Dark-field ability would also be nice, but I don't need high-power for that.

 

I'd appreciate your advice and thoughts on this bow.gif.

 

Thanks,

Daniel.


Edited by db2005, 26 October 2019 - 12:00 AM.

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#2 rzgp33

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Posted 25 October 2019 - 01:02 AM

I have 4 old microscopes, and one of them is a CH. I'm generally happy with it, though I can't get any good images through it yet. Adding a camera to a microscope to get *good* images seems  to be a hard thing to do.

 

I need to get a properly matched photo eyepiece and matched objective.

 

I have no doubt that newer scopes would offer advantages, but  you can also DIY  an LED lamp and the condenser is a standard size so a Amscope darkfield condenser should fit.

 

Apart from the usual comments about the quality of the eyepiece, objective and condenser, most good microscopes these days are infinity corrected, and are probably routinely optically better than they were years ago.

( I have zero evidence ti back that assertion up)

If you are just using the standard eyepiece and objectives for the CH then a new Olympus scope will be  better, how much better I don't know.

 

I know its getting hard to buy affordable Olympus/Nikon finite (DIN 160)  Plan objectives.

 

I think photography will be easier with a carefully chosen modern scope, but be careful, Astrophotography is a money pit, and so is Photomicroscopy!

 

If I had the money I would want to get a nice new $US10k system but I would also need to add microscope cameras etc, and then I'd probably stop and think if I really wanted the Losmandy G11 + nice Apo instead :)

 

Brian

 


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#3 Microscopy

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Posted 25 October 2019 - 11:01 AM

Would you choose the young full blood racehorse or rather the old donkey?

Well, it all depends: if you would be into acceleration and speed, a bet on the races every once in a while, you should definitely buy the racehorse. On the other hand: if you would happen to be an Afghan or Indian farmer, dependant for transportation of your produce to the market, you would be stupid not to buy the donkey... 

And then there's the budget issue, lol.


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#4 j.gardavsky

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Posted 25 October 2019 - 12:32 PM

Hello Daniel,

 

the Olympus microscopes are quite a bit overprized in Germany, so I have decided for the old Leitz Dialux, which is much more widespread here around, and hence cheaper.

 

https://www.cloudyni...919-microscopy/

 

The 160 tube length Leitz APO planar objectives should have a good match to the old Olympus 160 tubes. You can also use the 170 objectives, when you correct the distance of the eyepieces, its all just about the tube length.

 

Microphotography, I am taking the afocal pics behind the EP, and it works with the APO objectives down to about 1.4 µm resolution.

 

Best,

JG

 

 


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#5 db2005

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Posted 26 October 2019 - 12:09 AM

Thanks for all the replies so far. I don't know too much about the intricate differences between different microscope brands, but I have learned (particularly with telescopes) that high quality simply doesn't come cheap, and sometimes it's better to get high-quality equipment second-hand that getting mediocre quality equipment new.

 

j.gardavsky:

Thanks for your advice and comments!

 

Since I live in Denmark any future equipment purchases will probably be made from German dealers. But I wasn't aware that Olympus microscopes are overpriced in Germany; from looking as prices it looks to me as Olumpus are among the most affordable of the Big Four (Zeiss, Nikon, Olympus, Leica). Can you elaborate what makes you believe Olympus is overpriced in Germany? And would you say that new Zeiss or Leica (both German made) offer more value for money in Germany?

 

Thanks,

Daniel


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#6 Microscopy

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Posted 26 October 2019 - 12:10 AM

JG and Daniel: 75 - 100 Euros is a "normal" price for a second hand basic CH (CHC: the one with the mirror and monocular tube) in average condition, in Belgium and The Netherlands.

I consider that a fair price for what it is: Olympus put the CH-series on the market in the mid 1970's as: "... for practical laboratory teaching applications ...", see: https://www.olympus-...eum/micro/1976/. In other words: a sophisticated high school lab/entry level college/university lab microscope.

So comparing it with top notch, high grade research microscopes, very well maintained and serviced on a regular basis up to the highest standards no doubt, is not what I would call an honest comparison.


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#7 db2005

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Posted 26 October 2019 - 12:38 AM

JG and Daniel: 75 - 100 Euros is a "normal" price for a second hand basic CH (CHC: the one with the mirror and monocular tube) in average condition, in Belgium and The Netherlands.

I consider that a fair price for what it is: Olympus put the CH-series on the market in the mid 1970's as: "... for practical laboratory teaching applications ...", see: https://www.olympus-...eum/micro/1976/. In other words: a sophisticated high school lab/entry level college/university lab microscope.

So comparing it with top notch, high grade research microscopes, very well maintained and serviced on a regular basis up to the highest standards no doubt, is not what I would call an honest comparison.

Thanks for the clarification. It surely makes sense that when comparing prices that we whould compare apples to apples.

 

And if buying new, It seems to be that the Olympus CX23 and Zeiss PrimoStar are targeted at the same audience, priced reasonably similarly. Would you say either of these microscopes would be a good choice - or is a hobbyist better served by finding a older, refurbished lab grade microscope? I'm still trying to understand how much the optics in microscopes have improved since my Olympus CH microscope was made probably in the late 1970s. Also, I am under the impression that microscopes normally depreciate in value pretty quickly mainly because they often degrade due to poor handling and storage, poor maintenance and normal wear, fugus, etc. So buying used equipment seems to me a bit like a lottery ticket.

 

What I would be mainly looking for in a factory new microscope is: better (and clean, fresh) optics, cool LED illumination, better eye relief eyepieces for using with eyeglasses, ability to get spare parts and accessories easily (my CH microscope doesn't even have a filter holder, so I had to tinker with it and improvise something for dark-field microscopy), long warranty.

 

Is this making sense or am I missing something?


Edited by db2005, 26 October 2019 - 01:08 AM.

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#8 j.gardavsky

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Posted 26 October 2019 - 05:21 AM

Hello Daniel,

 

I find the Olympus APO microscope eyepieces, and some other accessories, like the interference filters for the fluorescence, much higher priced than the old Leitz APOs, filters, etc.

 

If I would buy "used but still manufactured", then this would definitely be the Leica HC system, as I am also using the Leica HC Plan S eyepiece in astronomy, and at f=25mm it beats anything coming from the Far East,

 

https://www.cloudyni...my-microscopes/

 

Last year, a Leica lab microscope system worth of $$,$$$ in Ingolstadt has been in auction, and the winning bid has been under 300 EUR. And this leica has been made in Germany, not from Singapore.

 

So I would not hurry, just waiting on the chance of your life,

JG


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#9 db2005

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Posted 27 October 2019 - 01:21 AM

Perhaps it's time to add some background information that catalyzed bringing my questions about: About 5 years ago I purchased a Euromex BioBlue microscope with Semi-Plan objectives, for hobby purposes. Although the scope looks pretty and is functional I did find the optics to be clearly outclassed by my much older Olympus microscope microscope, even in its fairly basic configuration (4x and 10x achromat, 40x PL and 100 H which I never use because I never exceed 400x). Both contrast and resolution are better in the Olympus CH; things just look more vivid and come more to life in the older optic. To be fair, I was not exactly shocked, as the Euromex scope cost just around 320 EUR and was made in China. So, just like with astronomical telescopes, I see my experience as a confirmation that optical quality is a Real Thing, but that experience has brought about many other questions. I don't normally have access to professional microscopes so I don't know what kind of optical quality to expect at different price levels.

 

For instance: How much does one need to spend today on new equipment to exceed the performance of my Olympus CHA? If you were tasked with "upgrading" from a vintage Olympus CH microscope, which Olympus microscope would you choose? A CX23 with Plan objectives (stock configuration)? A CX33 or CX43 in stock configuration or with upgraded microscope objectives?

 

Or, alternatively: In your experience, how much money does one need to spend on a higher-end microscope from one of the other brands than the Big Four (i.e. not Nikon, Leica, Olympus, Zeiss) to get a better microscope than the Olympus CH? 1000 USD? 2000 USD? More?

 

Although I am a sucker for pretty mechanical things, I'm not overly worried about the (limited) use of (quality) plastic components in a microscope; I am able to take good care of my instruments and they won't be exposed to unsupervised children; my main concern is optical quality ensuring vivid contrast and immersive, pretty views.

 

I would appreciate if you would share your thoughts on this.



#10 j.gardavsky

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Posted 27 October 2019 - 11:35 AM

Hello db,

 

to answer your question, a side-by comparison of different optics would be necessary. Unfortunartely, I can't do it, as I don't have other optics makes, and after comparing my Leitz with Zeiss, I have decided for Leitz.

 

Hoping, somebody with an Olympus equipment will jump in to help,

JG


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#11 rzgp33

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Posted 28 October 2019 - 01:30 AM

I think a CX33 would be good, but if I had the money I would probably go with the Nikon system.

Again for no good reason. I used them at Uni and was always impressed

 

I'd look at the Nikon Eclipse E200 student scopes. They seem to do well across the board. The base Nikon glass is excellent.

and are ~ $A3500 which I think is ~EU2100.

 

A step up would be the Niko Eclipse  Ci($US7-10k).... its hard to know until you have some hard requirements. Typically a research lab would go to a vendor and say "we want a scope that will do x y z"

Again I'd choose infinity optics, only because I have all finite scopes, and you yearn for what you don't have smile.gif

 

I'm looking for one old Olympus Photo eyepiece, the NFK 1.67... I saw one on a site the other day for $US800 whew! too rich for my blood

 

I'm currently reading the documents on Alan Woods Olympus site ... http://www.alanwood....icroscopes.html ( required reading for an old Oly owner)

One of them is  http://www.alanwood....-microscope.pdf

 

On page 15 of this brochure Olympus prints a comparison of achromat and apochromat objectives. Given that the cost is so much higher is the difference worth it?

 

Could you try getting a new eyepiece and matched objective? That may be all you need.

 

Brian


Edited by rzgp33, 28 October 2019 - 01:32 AM.

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#12 Microscopy

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Posted 30 October 2019 - 06:31 PM

I can't really comment on the new versus second-hand issue, as I don't buy new microscopes, but I see some new microscopes every once in a while and I'm usually not all that impressed...

 

BTW: many entry-level microscopes, also from famous brands, like the Zeiss Primostar, are build by Meji and/or Motic.

 

If you're dissatisfied with the image quality of your microscope, there are several ways to improve it: better corrected objectives (fluorites, (plan)apochromats), but you should keep in mind that they only give their best performance when used with a better corrected condenser (aplanatic or aplanatic-achromatic) and high grade, matching eyepieces.

Olympus designed the CH at the time with compatibility with the BH of the same era in mind: most parts of the BH will fit the CH and the other way around.

Besides that: your microscope is a classic 160mm tube length microscope: there's plenty of choice in objectives and eyepieces, but you will be stuck with Olympus for the condenser (unless you would be a very gifted mechanic who can adapt another condenser to your microscope stand).

For low magnifications an achromatic objective can be used as a fully corrected achromatic condenser. For that purpose some brands had at the time a condenser slider with RMS screw tread.

 

All objectives designed for 160 mm have the same standard RMS screw tread. The only exceptions are the objectives of some excursion microscopes. All eyepieces of that era have the same diameter (23.2 mm). All brands had at that time eyepieces with high eye relief, but some are ver wanted (example: some zeiss KPL's with the spectacle symbol), thus very expensive.

 

Also: refurbishing and properly aligning a microscope can dramatically improve image quality, but I only know a few trustworthy companies in that field in Europe. They usually do a splendid job, but they're not cheap and they can't do miracles, even though they try sometimes. 

 

If your microscope is worth the investment is another matter... I have a few CH's and I wouldn't put much money in them, as they pale in comparison with some larger microscopes I have as well. They remain my favourites when I go out to give a microscopy workshop in an elementary or a junior high school, but putting money in them? No. they're fine as they are.

 

If you would think of buying another second-hand microscope: be very suspicious for "refurbished" microscopes or for microscopes "serviced on a regular basis". I've seen plenty of those and most of the time "refurbishing" and "servicing" means putting another blob from whatever can of grease was available on top of the blob from last year. Also: I always wondered about the large amounts of small parts (screws, spacers etc.) that apparently went missing during those servicings...


Edited by Microscopy, 30 October 2019 - 06:54 PM.

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#13 db2005

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Posted 31 October 2019 - 01:01 AM

Thanks for all the good advice! waytogo.gif . It is also good to know that the CH is a 160 mm system, I had been wondering about that. And thanks for the heads-up warning about problems with so-called "refurbushed" microscopes. The advice makes good sense to me - microscopes are much more complex instruments than telescopes, and with so many mechanical parts and optical components, so many more things can go wrong during disassembly and reassembly.

 

I'm not displeased with my CH - definitely not, as its is providing much better views than any of my other microscopes, and also has the binocular head which is more comfortable to use than my other instruments with monocular head. But it is showing its age, so I was wondering how much one should invest to get a significant improvement in terms of optics, observing comfort (long eye relief eyeglasses), etc. It seems like perhaps the CX23 won't be much of an improvement, if any, since this microscope too (like the CH) is targeted at the educational market and is made for simplicity of use rather than extensibility. Next step up is the CX33, but that too is a significant step up in price.


Edited by db2005, 31 October 2019 - 01:03 AM.


#14 db2005

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Posted 31 October 2019 - 01:31 AM

... I don't buy new microscopes, but I see some new microscopes every once in a while and I'm usually not all that impressed...

Very interesting... I am very curious... are these new microscopes from the Big 4 or some other lesser known brands? Which price level? And which aspects of the scopes leave you unimpressed? - Mechanics, optics, extensibility, fit/finish, etc.?

 

EDIT:

 

Hands-on experience has gradually taught me roughly at which price point astronomical telescopes and eyepieces become "high/end" or "premium" products, but I have too little experience with microscopes to have a firm understanding about which price level today would equate (or exceed) my vintage Olympus CH. For instance, is today's Olympus CX23 today's equivalent to the older Olympus CH, or would that comparison be too generous to the CX23? The CX23 has plan achromatic objectives though, which should seem like an improvement in its own right, all other things being equal.


Edited by db2005, 31 October 2019 - 11:42 AM.


#15 Microscopy

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Posted 01 November 2019 - 03:18 PM

A remark:

standard condenser diameter size

There's no such thing as a "standard condenser diameter size".

Zeiss proposed that at the time (37mm/1.456in), but there were very few takers. Actually, Olympus was one of the few.

 

Zeiss left the idea in favour of the principle of a condenser sliding horizontally in it's mount, which was already been worked on by Leitz. It was based on the idea of the Akehurst slider, which carried a replaceable condenser. As far as I know the idea in it's original form was used only once, by Reichert, in their iconic Zetopan microscope.

 

The only microscope in which Zeiss used their proposed standard was in their entry-level Standard Junior KF microscope of the 1950's. The next model higher up in the Zeiss Standard ecosystem, the Standard G(FL) had the horizontal sliding in condenser, which remained unchanged in the Zeiss Standards for some 40 years.

 

However, many microscope models, from all kinds of brands  (and including the CH) used for a long time condensers manufactured to the proposed Zeiss standard, including: Olympus CH, LOMO Biolam, Euromex LMS aka Ghuanzhu L-201, unidentified older Meopta microscopes, ...

Olympus definitively left the idea of a common standard on condenser diameter somewhere between the CH/BH and the CH-2/BH-2. In the CH-2/BH-2 they went fully for their own version of a condenser sliding horizontally in it's mount, leaving backward compatibility, and the proposed Zeiss standard, behind.

 

 


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#16 Microscopy

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Posted 02 November 2019 - 04:08 AM

Very interesting... I am very curious... are these new microscopes from the Big 4 or some other lesser known brands? Which price level? And which aspects of the scopes leave you unimpressed? - Mechanics, optics, extensibility, fit/finish, etc.?

(...)

 

Those were/are new microscopes, including some of "the big 4" except for Nikon, but mostly from smaller brands (actually resellers) like Bresser, Euromex and such, microscopes in the price range 100-2000 €.

I didn't made a statistic analysis of what I've seen/see, that would be impossible due to the too small a sample size, and in general most of those microscopes would/will work as intended (for sure on the company's shareholders side), but those that weren't up to their task paint a grim picture of Murphy's law (in the best case scenario) or gross negligence and total disrespect for users (in the worst case scenario).

 

I've pretty much seen it all, I suppose: microscopes new out of the box with loose or missing screws, with broken gears, with unacceptable amounts of play, backlash and overshoot in the focussing controls, poorly aligned (or not aligned at all) stands, uncentered condensers, uncentered diaphragms within the condenser, condensers with parts missing, objectives with magnifications and apertures deviating more than +/- 10% from proclaimed values, non-existent parfocality, unusable nosepieces, missing stages (!!! yes...).

Paint and finishing were always perfect though, lol.

 

Trust me: compared to some of those, the CH remains a top class performer in it's league. As I suggested earlier in a comment here: it's the donkey. It's ugly but reliable, you hate it sometimes for it's shortcomings, but it keeps going on, no matter what. 

 

Many of the problems you mentioned are not that hard to solve: 

 

  • critters being cooked due to heat radiation from the light source: use a IR blocking filter. These can easily be scavenged from old slide projectors (the thick blue-green piece of glass found immediately in front of the bulb). there's no solution for critters being cooked due to heat transmission through the microscope stand. One of the reasons why I'm a firm believer of microscopes with build-on illumination or free standing illuminators
  • Wrong color temperature due to tungsten illumination: use a blue filter. KB12 is kind of a golden standard for that
  • spare parts hard to come by/upgradebility: welcome to the universe of second-hand microscope users. It took me + 10 years to complete my Zetopan. I found most parts not on eBay, but on small, local websites, advertising parts in ads like:"scientific-gear-I-don'know-what-it-is-but-perhaps-you-do". Try to take a Zen approach: the journey is more important than the destination
  • the eye relief/astigmatism issue: Olympus offered a pair of 10x eyepieces with high eye relief at the time. Finding them might be difficult, but not impossible.

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#17 db2005

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Posted 02 November 2019 - 06:09 AM

 

Those were/are new microscopes, including some of "the big 4" except for Nikon, but mostly from smaller brands (actually resellers) like Bresser, Euromex and such, microscopes in the price range 100-2000 €.

I didn't made a statistic analysis of what I've seen/see, that would be impossible due to the too small a sample size, and in general most of those microscopes would/will work as intended (for sure on the company's shareholders side), but those that weren't up to their task paint a grim picture of Murphy's law (in the best case scenario) or gross negligence and total disrespect for users (in the worst case scenario).

 

I've pretty much seen it all, I suppose: microscopes new out of the box with loose or missing screws, with broken gears, with unacceptable amounts of play, backlash and overshoot in the focussing controls, poorly aligned (or not aligned at all) stands, uncentered condensers, uncentered diaphragms within the condenser, condensers with parts missing, objectives with magnifications and apertures deviating more than +/- 10% from proclaimed values, non-existent parfocality, unusable nosepieces, missing stages (!!! yes...).

Paint and finishing were always perfect though, lol.

 

Trust me: compared to some of those, the CH remains a top class performer in it's league. As I suggested earlier in a comment here: it's the donkey. It's ugly but reliable, you hate it sometimes for it's shortcomings, but it keeps going on, no matter what. 

 

Many of the problems you mentioned are not that hard to solve: 

 

  • critters being cooked due to heat radiation from the light source: use a IR blocking filter. These can easily be scavenged from old slide projectors (the thick blue-green piece of glass found immediately in front of the bulb). there's no solution for critters being cooked due to heat transmission through the microscope stand. One of the reasons why I'm a firm believer of microscopes with build-on illumination or free standing illuminators
  • Wrong color temperature due to tungsten illumination: use a blue filter. KB12 is kind of a golden standard for that
  • spare parts hard to come by/upgradebility: welcome to the universe of second-hand microscope users. It took me + 10 years to complete my Zetopan. I found most parts not on eBay, but on small, local websites, advertising parts in ads like:"scientific-gear-I-don'know-what-it-is-but-perhaps-you-do". Try to take a Zen approach: the journey is more important than the destination
  • the eye relief/astigmatism issue: Olympus offered a pair of 10x eyepieces with high eye relief at the time. Finding them might be difficult, but not impossible.

 

Thank you very much for taking the time to elaborate on your points ... much appreciated waytogo.gif. I seems like the CH is already such a good microscope that finding a significant step up from the CH will be difficult and require a substantial investment.

 

I have taken your advice and ordered myself a photographic KB12 filter to neutralize color balance.

 

As for the eye relief issue I just need to figure out which model of eyepieces to get. My current eyepieces say WF10X Bi. Since the CH is a 160mm system I am somewhat tempted to take a chance buying some new Wide-field long-eye-relief eyepieces which are fairly cheap, but I'm not sure if I will regret it...



#18 Microscopy

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Posted 02 November 2019 - 08:46 AM

Yes well, I'm feeling kind of strange, playing the devil's advocate on behalf of a microscope I don't even like all that much, from a brand of which I'm not exactly a hughe fan.


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#19 Microscopy

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Posted 03 November 2019 - 03:30 AM

WF10x were the standard eyepieces, even though Olympus put them on the market as "high eye point". High(er) eye relief eyepieces were stamped HEPWF10x, with in both cases "Bi" added on matching pairs. In both types F.N. was 20 and price for both types was about the same.

 

Alan Wood's website, already mentioned here by rzgp33 (#11), contains a wealth on information on Olympus microscopes, including the CH and the fantastic manuals on the BH-2, written by Carl Hunsinger. 

 

If you would ever think on upgrading to another microscope, it's important to consider the exact place of your microscope within the field: the CH was put on the market, I mentioned it earlier,  as "... for practical laboratory teaching applications ...".

It was in the same league as the Wild m12, the Will Wetzlar Bx/Vm/Vb 200/300 series, the Reichert Neopan/Diapan, the Kyowa Medilux, the smaller Zeiss Standards, the grey Leitz laborlux k/d/s of that era, ...

All microscopes designed "for practical laboratory teaching applications" AND for routine work in the human/veterinary medecine clinical lab, such as counting red/white blood cells and reticulocytes, urine sedimentation slides, detection and identification of worm eggs, fungi spores etc., Gram, Ziehl-Neelsen and Schaeffer-Fulton stained smairs in the bacteriological lab and so on.

They were designed to withstand improper use and even abuse from less well trained lab technicians (no doubt there was some prejudice there on behalf of the designers...). 

When flow cytometry analysis came into vogue (the late 1970's) many of those people lost their job and routine clinical lab microscopes became, at least partially, redundant.

 

So there you have it: your microscope is the work horse (I'm getting a bit fed up with the mule analogy I made earlier). It's not the best microscope ever, but definitely not the worst either. It's not a research microscope, it wasn't intended to be one, but at least I can put it on the table without help and it only needs a minute to set it up. 

Of course, images from a Wild m20, equipped with Wild Fluotars or an Olympus BHS, equipped with S-plans and Pl-apos are better. But worth the difference in price? No, not in my book.


Edited by Microscopy, 03 November 2019 - 04:45 AM.

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#20 db2005

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Posted 03 November 2019 - 07:07 AM

Brilliant explanations above waytogo.gif  Thanks a lot for taking the time!



#21 Microscopy

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Posted 03 November 2019 - 03:28 PM

Thank you.

I would like to ad another thing: in #7 you mentioned: "... my CH microscope doesn't even have a filter holder, so I had to tinker with it and improvise something for dark-field microscopy...".

 

Whenever one buys a second-hand microscope, you can bet that there's a very high chance some things will be missing. Classics are: the manual, the key of the microscope case, the bulb holder of the illuminator, and pretty much everything that isn't tightly fit to the microscope with a few screws, like, for example, the push in filter holder for the CH, fitting into the condenser... 

Never gave it much thought, but now that you mentioned it, I took a closer look at my 2 CH's and yes, in both the filter holder is missing as well. But I do have the key of one of the cases, lol.


Edited by Microscopy, 03 November 2019 - 03:45 PM.

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#22 db2005

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Posted 03 November 2019 - 10:54 PM

Luckily I found a copy of an Olympus CH manual and based on that it seems like I can use the top of the illuminator as a filter holder for a 45 mm filter. I also tried placing a piece of blue glass in it and it does indeed provide a more natural "white" color balance. Now, if the Olympus 45 mm dark field patch stop also works when put straight on top of the illuminator (I just ordered one, so I'll know for sure when I receive it in a few days), I'll be quite happy...



#23 Microscopy

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Posted 04 November 2019 - 04:06 AM

(...)  Now, if the Olympus 45 mm dark field patch stop also works when put straight on top of the illuminator (I just ordered one, so I'll know for sure when I receive it in a few days), I'll be quite happy...

It won't work: those DF stops and their corresponding condensers are designed to work only when the DF stop is mount as close as possible to the condenser diaphragm. 

Also, don't expect too much: those systems with a DF stop in combination with a regular condenser can only provide DF for objectives with N.A.'s up to around 0.50, meaning in achromats: 4,10, 20.

 

Sometimes (but rarely) it's possible to use them with a 40/0.65, when the DF stop is placed within the condenser, just beneath the front lens.

 

Also: DF images can be disappointing sometimes. I don't want to delve in optical theory too much, but microscopes in basic configuration are usually equipped with an abbe condenser.

"abbe condenser" is a marketing term, using Ernst Abbe's name to suggest very high quality.

The real name of the device is: "uncorrected condenser", meaning it's not corrected for chromatic aberration, nor for spherical aberration.  Now, as a general rule of thumb, one can say that (residual) aberrations become more and more apparent the further the beam of light is away from the optical axis of the device. In DF only the periphery of the optical system is used to provide the cone of light, resulting sometimes in very noticeable C and S aberration in the image.

 

For DF in higher magnifications you'll need a "real" cardioid immersion DF condenser. Those might be difficult to find for the CH, but an alternative might be the older Russian LOMO OL-13 DF condenser. That one is slightly larger in diameter (37.00mm) compared to the one of the CH (36.85mm), but that shouldn't be all that hard to solve, using some sandpaper. It's without much danger, as the optics can easily be detached (in one single piece) from the condenser body. 

Those OL-13's appear on a regular basis on Ebay, see for example: https://www.ebay.com...AQAAOSwJmRdZOn3

 

Keep in mind though, that those condensers are usually advertised as having an N.A. of around 1.20. What they don't tell you is that that's the outer cone of light, while the limiting factor is the inner cone, which is usually somewhere around 0.8 - 0.9.

That's the reason why that LOMO condenser has in the package a funnel stop to place in the 90/1.25 immersion objective, limiting the N.A. of the objective. It's also the reason why some high end/high magnification/high N.A. objectives have a build in diaphragm. And that answers a question in another thread as well, lol.

 

Some brands have put so-called "wide field" DF condensors on the market, for example Reichert. Those had an outer cone of around 1.40 and an inner cone of around 1.20. They were, you guessed it, very expensive.

 

 

Don't you know someone who owns a lathe? It can't be all that hard to make a few filter holders from some aluminum stock...

It all depends on local legislation and habits I suppose, but for that kind of small jobs, we go here to the local technical high school. Those teachers are happy to accept that kind of work against the material cost and a small donation to the school fund, or a small favour in return.

The local technical high school here did a great job in making some spare parts for a few of my microscopes. In return I overhauled their very old material microscope. Everyone happy...


Edited by Microscopy, 04 November 2019 - 04:56 AM.

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#24 db2005

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Posted 06 November 2019 - 11:38 AM

I took a chance and got myself some new generic 10x/18mm wide field eyepieces with high eyepoint off Ebay. I did have some doubts, but they work extremely well, and have completely solved my problem with using eyeglasses. They even have a slightly wider AFOV than the original eyepieces.

 

Thanks for all the great advice so far!



#25 db2005

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Posted 24 January 2020 - 11:11 AM

Update: 1970s Olympus CHA vs modern Olympus CX31 w/UIS2 optics:

 

Since the latest post in this thread I decided to take a leap of faith:

 

I got myself a second-hand Olympus CX31 microscope in excellent optical and mechanical condition, with 4x, 10x, 40x and 100x UIS2 objectives. I didn't have an opportunity to try before buying, so the only indication of the expected performance was my quick session with a Olympus BX51 lab microscope which impressed me much, also sporting Olympus' UIS2 optics. But, I recently learned that this microscope is actually in the ~$40K class (with all bells and whistles, phase contrast, polarization, metallurgical objective, trinocular head, etc), and not in the $10K class as I wrote in the OP. So... I was a bit hesitant. Would a CX31 microscope costing significantly less fall short in terms of optical quality and performance? On the other hand, Olympus UIS2 optics are Olympus UIS2 optics, and all I wanted was excellent optics useful for brightfield and darkfield. So I took the plunge and placed the order. 

 

I haven't regretted it. The CX31 is a very, very nice instrument with truly excellent optics.

 

In summary:

 

The optics in the CX31 are remarkably good and are a healthy step up from my vintage Olympus CHA microscope. Field of view is significantly larger, eye relief is excellent and field flatness is absolutely perfect as far as I can visually tell: No drop off in terms of sharpness, contrast and no additional false color at edges. Sharpness and contrast and richness in color are equally impressive. Color correction is very impressive too, leaps and bounds ahead of many other "achromatic" objectives I've tried. Mechanical quality seems roughly on par with my Olympus CHA, yet with somewhat more refinement and with some modern enhancements, such as the rackless stage. The CX31 does contain more plastic parts than the CHA, but they are good quality plastic parts.

 

But are the optics as good as those on the BX51 microscope I tried? I can't tell for sure as I can't compare them directly, but if my memory serves me right, I would say the optics are very, very similar in performance. Of course the BX51 has 22 mm eyepieces, and the CX31 "only" sports 20 mm eyepieces, so the field of view is somewhat smaller in the CX31. Other than that I would say the optics and views of the CX31 are every bit as good as those I tried on the BX51.




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