Some problems with my microscope

Everything relating to microscopy hardware: Objectives, eyepieces, lamps and more.
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Micro_UTRG
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Joined: Wed Jun 24, 2020 7:55 pm

Some problems with my microscope

#1 Post by Micro_UTRG » Wed Jul 08, 2020 1:32 am

Hi everyone,
I have several questions regarding my microscope: I bought an Olympus CH-2 with a set of D Achromats and I recently bought a Short barrel FL 40x 0.75. The Shrot barrel objective requires much closer focusing distance than my microscope can provide.

How can I work around the short barrel without sacrificing the distance of the slide to the condenser? I don't mind having to refocus when changing objectives, but it would be nice to have them being parfocal.

I would also like to know what are my options to attach a Nikon D7100 to my microscope without investing too much money. I don't have a trinoc head, but I'm planning on buying one.

What condensers would benefit my image quality? My microscope came with this cheap condenser ''supposedly 1.25 NA'' that I suspect isn't the original, the cone of light is very wide and the only element is nowhere near the slide.
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PeteM
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Re: Some problems with my microscope

#2 Post by PeteM » Wed Jul 08, 2020 2:49 am

A few thoughts, M-UTRG,

First, it looks to me like your condenser is missing its top lens. Just getting one that's complete would be a big step up. Right now it's only good for maybe the 10x. The CH-2 is a decent scope and I think you'll be happy with it.

If you already have a 40x DPlan objective, I'm not sure trying to put a parfocal extender on your old short barrel 40x Fl is worth it. It really wants the right tube length, the right eyepieces, etc. to get the most out of it. And that "most" includes a good objective, but not the most modern coatings. If I recall, there may be a user here (Viktor) looking for short barrel objectives for an older DIC system - though he may be looking for an Apo. I'd be inclined to sell it to someone using all short barrel objectives.

Charles Krebs and others have information on camera hook ups to a trinocular head. It should be the same as BH-2 and a BH-2 trinocular with its 20mm wide field should also be desirable. This link may also be helpful: https://www.lmscope.com/en/Nikon_d7100_ ... py_en.html

Micro_UTRG
Posts: 11
Joined: Wed Jun 24, 2020 7:55 pm

Re: Some problems with my microscope

#3 Post by Micro_UTRG » Wed Jul 08, 2020 4:16 am

Thanks for the response.
I only had a 4x, 10x, 20x and a 100x, so a 40x was a must. Could you tell me a bit more about the extender? Advantages and Disadvantages.
Also, what are some good and rare Condensers? Say, below 150 USD.

PeteM
Posts: 1428
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Location: N. California

Re: Some problems with my microscope

#4 Post by PeteM » Wed Jul 08, 2020 5:18 am

As suggested earlier, just a complete 1.25 na Olympus condenser that fits your scope would work well. Olympus also made a better color corrected 1.4na condenser, but the extra $100 it might cost won't be all that obvious until you, say, start taking photos with a 100x oil immersion lens, with the condenser and objective oiled to the slide.

At low magnifications you can often just add about an 8mm parfocal extenders (and some shims) to get a short barrel objective parfocal with the rest.

At 40x you need a bit of correction because the tube length ends up too long. It's no longer 160mm but more like 168mm. Far as I know the Leitz "Plezy" adapter is the only one made. It won't have quite the right corrections. It will cost (used) about as much as the 40x DPlan. Your short barrel Olympus will want different eyepieces for perfect correction. And the whole thing will be off about half a mm. in focus due to the differences between Olympus and Leitz short barrel objectives. Which is why the previous suggestion to sell the short barrel Olympus and get a long barrel one.

There are two problems with mismatched focal distances. First, the inconvenience of re-focusing. Second, at some point we all forget and crash one of the 45mm DIN objectives into a slide, after viewing with one at 36mm+ (or 34mm in the Leitz short barrel case).

Good luck.

Micro_UTRG
Posts: 11
Joined: Wed Jun 24, 2020 7:55 pm

Re: Some problems with my microscope

#5 Post by Micro_UTRG » Wed Jul 08, 2020 3:18 pm

PeteM wrote:
Wed Jul 08, 2020 5:18 am
As suggested earlier, just a complete 1.25 na Olympus condenser that fits your scope would work well. Olympus also made a better color corrected 1.4na condenser, but the extra $100 it might cost won't be all that obvious until you, say, start taking photos with a 100x oil immersion lens, with the condenser and objective oiled to the slide.

At low magnifications you can often just add about an 8mm parfocal extenders (and some shims) to get a short barrel objective parfocal with the rest.

At 40x you need a bit of correction because the tube length ends up too long. It's no longer 160mm but more like 168mm. Far as I know the Leitz "Plezy" adapter is the only one made. It won't have quite the right corrections. It will cost (used) about as much as the 40x DPlan. Your short barrel Olympus will want different eyepieces for perfect correction. And the whole thing will be off about half a mm. in focus due to the differences between Olympus and Leitz short barrel objectives. Which is why the previous suggestion to sell the short barrel Olympus and get a long barrel one.

There are two problems with mismatched focal distances. First, the inconvenience of re-focusing. Second, at some point we all forget and crash one of the 45mm DIN objectives into a slide, after viewing with one at 36mm+ (or 34mm in the Leitz short barrel case).

Good luck.
Wow! I just got the 40x and didn't think I would get rid of it so fast. More so when I got it so cheap.

Speaking of the condenser, I will try to get another one. But for now I've used a convex-flat lens to narrow the light cone. How much of an improvement do I expect to see with a 1.3 NA Zeiss condenser like this one[https://www.ebay.com/itm/Zeiss-Vintage- ... 3855067239][/url]?

Last question (I think), In the future I'll probably buy a BH-2 because I've seen, with the right equipment, it's as good as the newer infinity microscopes. Can you confirm this?

apochronaut
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Re: Some problems with my microscope

#6 Post by apochronaut » Wed Jul 08, 2020 3:51 pm

Why are you looking at a Zeiss condenser to put on an Olympus? A second question is: why do you think that modern infinity microscopes are a pinnacle that older microscopes need to be compared to?

Micro_UTRG
Posts: 11
Joined: Wed Jun 24, 2020 7:55 pm

Re: Some problems with my microscope

#7 Post by Micro_UTRG » Wed Jul 08, 2020 4:26 pm

Well, the condenser is cheap, high NA and of metal construction, I'm a fan of rare looking equipment. It comes with its own stand, but if there is a problem I would rather use an Olympus. :D
Regarding the BH2 vs Infinity scopes, the newer objectives have improved coatings, aspherical elements and so on that make them incrementally better: but as I said, the BH-2 can be almost as good, as I have seen previously. Don't you think?

Zuul
Posts: 212
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Location: California

Re: Some problems with my microscope

#8 Post by Zuul » Wed Jul 08, 2020 5:34 pm

Micro_UTRG wrote:
Wed Jul 08, 2020 4:26 pm
Well, the condenser is cheap, high NA and of metal construction, I'm a fan of rare looking equipment. It comes with its own stand, but if there is a problem I would rather use an Olympus. :D
But does it work without further effort? "Just fits & works" has a value, too!
Micro_UTRG wrote:
Wed Jul 08, 2020 4:26 pm
Regarding the BH2 vs Infinity scopes, the newer objectives have improved coatings, aspherical elements and so on that make them incrementally better: but as I said, the BH-2 can be almost as good, as I have seen previously. Don't you think?
I believe Apochronaut was calling into question whether modern infinity scopes are "always" better. Improved coatings? Sometimes yes, sometimes no; it depends on what is being compared. Aspherical elements can be beneficial in some cases, but aren't, in themselves, necessarily an improvement. Regardless, they have been available for many decades now.

MicroBob
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Re: Some problems with my microscope

#9 Post by MicroBob » Wed Jul 08, 2020 6:28 pm

That is a condenser for the Zeiss Standard Junior with sleeve fit. This microscope was intended to be used with a mirror and a light source a bit away. It might not be the best choice for a microscope with the light in the foot. I would suggest an Olympus condenser. If you need more parts you might better buy a complete microscope.

When you buy a new 25000€ microscope it will be good and it will be infinity optics. This doesn't mean that infinity optics are necessarily better. :D

Bob

apochronaut
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Joined: Fri May 15, 2015 12:15 am

Re: Some problems with my microscope

#10 Post by apochronaut » Wed Jul 08, 2020 8:24 pm

Micro_UTRG wrote:
Wed Jul 08, 2020 4:26 pm
Well, the condenser is cheap, high NA and of metal construction, I'm a fan of rare looking equipment. It comes with its own stand, but if there is a problem I would rather use an Olympus. :D
Regarding the BH2 vs Infinity scopes, the newer objectives have improved coatings, aspherical elements and so on that make them incrementally better: but as I said, the BH-2 can be almost as good, as I have seen previously. Don't you think?
Condensers also have focal lengths. Usually , the front focal length is not all that much different between two of the same N.A. but the back focal length can vary widely, depending on where the light source is that the condenser was designed to receive it's illumination from. Many older condensers had an infinity back focal length and when built in illuminators arrived on the scene the focal length was shortened to match the condenser to illumination source distance. Yes, an even field background relies on defocusing the condenser but this needs to be taken into account too. Two .90 N.A. condensers for instance will defocus to provide an even background illumination and an ideal light cone with the systems they were engineered for. If the back focal length difference between them is great enough, when one of them is moved to the other situation, it will either not be capable of defocusing ideally or if it can be moved to such a condition, not provide an ideal light cone. Preference and physical necessity is for the ideal light cone to be maintained usually, so the ability of the condenser to produce an even and aberration free illumination field can suffer as a result.

It is true that infinity corrected objectives are more likely to have been made when the peak of optical technology was at hand. However, the classes of objectives still exist and even apochromats as old as the first world war, can be relied on to provide superior resolution to that of a brand new achromat fresh out of the factory. There may be a difference in flatness and breadth of field with such an extreme example but full 18 to 20mm fields have been around since at least the 50's. Choosing a microscope objective is like choosing a skipping stone. It isn't the size or the weight or anyone's name on the stone . It's how flat and even and free of imperfections it is.

Micro_UTRG
Posts: 11
Joined: Wed Jun 24, 2020 7:55 pm

Re: Some problems with my microscope

#11 Post by Micro_UTRG » Thu Jul 09, 2020 1:52 am

Thanks everyone, That is something I didn't thought of.
I'm going to get an Olympus condenser, since most of you agree it is best.
I will also sell my 40x Objective and try to get a new Long Barrel one. Are other brand Objectives totally compatible?

deBult
Posts: 169
Joined: Tue Jul 16, 2019 3:20 pm

Re: Some problems with my microscope

#12 Post by deBult » Thu Jul 09, 2020 2:28 am

Objectives and eyepieces need to match as they work TOGETHER in correcting errors in the optical path.

In practice this means you need to stick with eyepiece and objective combinations of the same brand AND within this brand in the same development period.

For an Olympus CH-2 this means LB objectives, CWHK or WHK eyepieces and NFK photo eyepieces.

For condensers: CH2-PCD UNIVERSAL, CH2-POL, CH-2 (or CH) CD Abbe. Plus most of the BH series condensers (not the BH-2 range with 1 exception: the BH-2 PC Phase contrast).
The CH2-PCD universal is by far my favorite on my CH-2: as this one combines bright field, phase-contrast for 10* and 40* objectives and dark field, it is a bit “plastic” though.

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