Improving a toy microscope..add a condenser?

Everything relating to microscopy hardware: Objectives, eyepieces, lamps and more.
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Scoper
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Improving a toy microscope..add a condenser?

#1 Post by Scoper » Sun Feb 05, 2023 3:02 am

Recently I read a number of site discussions concerning toy microscopes and improving them.

Thank you posting such info…very interesting.

One of the comments noted that some toy microscopes had a condenser.

Where would one find a suitable lens to improve a toy microscope today?

Thanks

BramHuntingNematodes
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Re: Improving a toy microscope..add a condenser?

#2 Post by BramHuntingNematodes » Sun Feb 05, 2023 6:11 am

A condenser might make it a little brighter, but I doubt it will help the resolution too much. Toy objectives are not great. My experiments with toys and condensers could never make great images.

I wouldn't bother trying to supe up a toy. You'd end up replacing every piece, and by then you should have just gone with a real microscope.
1942 Bausch and Lomb Series T Dynoptic, Custom Illumination

MicroBob
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Re: Improving a toy microscope..add a condenser?

#3 Post by MicroBob » Sun Feb 05, 2023 8:04 am

I once had a microscope that has cost 40€ new with quite acceptable objectives 4:1, 10:1 and 40:1. It was mainly let down by the very low numeric aperture of the illumination. I installed a small camera objective below the stage, oriented so the front lens faces the light source. This improved image quality a lot and the microscope was useable whithin it's limitations.

What you need is any kind of collecting optics that focuses the light rays from the light source into a light cone. Have a look at schematic microscope illustrations to see how this cone should look like and how to place it. A single strong collecting lens e.g. from a flash light can already do the job.

A second method is to install a light source with a wider diameter and not to use a condenser. This gives a softer, less directed light but still offers an improved numeric aperture.
Rolf describes this perfectly on his website: https://microscopyofnature.com/getting- ... microscope

While it is nice to use a very good microscope one can still observe a lot with a basic one as long as one knows how to do it right!

Chas
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Re: Improving a toy microscope..add a condenser?

#4 Post by Chas » Sun Feb 05, 2023 9:39 am

There are some inexpensive, new, complete condensers about:
Abbe from china.jpg
Abbe from china.jpg (79.09 KiB) Viewed 35535 times
This one has a largish diameter (~12mm) top lens.

I am not going to go against what Rolf Vossen put on that webpage except he seems to tangle his 'student-type' microscope with the real toy microscopes.

apochronaut
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Re: Improving a toy microscope..add a condenser?

#5 Post by apochronaut » Sun Feb 05, 2023 3:57 pm

There is a big difference between the hobby grade microscope Rolf Vossen is adapting in his article and a toy micoscope. That one is more rightly called a hobby or student microscope.

There are only limited attempts to achromatize the objectives used in most toy microscopes. Sometimes the higher power objectives have a doublet but usually the objectives are assembled in stacked air spaced columns of chip lenses. The N.A.s are poor as well. I have seen one that had a marked N.A. of .45 on a 40X objective . It had a rudimentary single lens plano convex condenser mounted in the stage aperture in order to brighten things up but the image quality was still poor and in no way capable of reaching the heights attained in Vossen's article.
Most modern toy microscopes are mainly plastic with plastic optics as well but some of the older ones had acceptable mechanical features, even a decent fine focus. There are small thread achromatic objectives made for certain hobby scopes and sold by Edmund amongst others. Those are quite good and if obtained cheap enough are the best way to utilize an older toy metal stand and get quality images.

Scoper
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Re: Improving a toy microscope..add a condenser?

#6 Post by Scoper » Mon Feb 06, 2023 10:08 pm

Thank you for the responses.

I am considering modifications to a toy microscope for field purposes in collecting pond samples.

The lack of field microscopes being available is frustrating…either they are very expensive either used or new or very few to be had. Meanwhile we have many used or new microscopes to choose from.

Any suggestions on this subject is welcome.

Thanks

apochronaut
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Re: Improving a toy microscope..add a condenser?

#7 Post by apochronaut » Tue Feb 07, 2023 1:34 am

Scoper wrote:
Mon Feb 06, 2023 10:08 pm
Thank you for the responses.

I am considering modifications to a toy microscope for field purposes in collecting pond samples.

The lack of field microscopes being available is frustrating…either they are very expensive either used or new or very few to be had. Meanwhile we have many used or new microscopes to choose from.

Any suggestions on this subject is welcome.

Thanks
I have done a little work on that and posted a bit about it. One of the problems is the objective size and the limited number of good objectives made with those thread sizes. It is not an impossible task but definitely patience will be required. Frank, or member zzffnn , a long time member has also done some work on that. Here is a bit of a discussion about the concept. https://www.microbehunter.com/microscop ... hp?t=15851

MikeBradley
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Re: Improving a toy microscope..add a condenser?

#8 Post by MikeBradley » Tue Feb 07, 2023 4:16 am

Not often mentioned in these discussion of portable microscopes is the Olympus MIC. I was made aware of these on reading "The Freshwater Microscopist" by Tony Pattinson and I've been happy with as my travelling microscope. It even comes with a protective moulded case. I added an LED, for my use that was all I needed for screening pond samples in the field and hobby use on holiday. I'm happy with it. Tony made more extensive mods, adding a condenser and fitting standard eyepieces. These units are often seen online and are reasonably priced.

https://www.ebay.com/itm/185621256061

Michael
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lorez2
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Re: Improving a toy microscope..add a condenser?

#9 Post by lorez2 » Tue Feb 07, 2023 4:55 am

I have quite a bunch of student microscopes that are like those being discussed here that are in varying states of restorability that I would be willing to trade to some enthusiastic person in the US for an authenticated bag of sand... remember, sand can be microscopic.

lorez2
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MicroBob
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Re: Improving a toy microscope..add a condenser?

#10 Post by MicroBob » Tue Feb 07, 2023 7:20 am

Here was a topic on portable microscopes: https://www.microbehunter.com/microscop ... ope+meopta
It is not difficult to find one for 200x combined magnification but becomes increasingly dificult to find something light an daffordable with higher magnification.

Scoper
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Re: Improving a toy microscope..add a condenser?

#11 Post by Scoper » Tue Feb 07, 2023 12:52 pm

If one would want to add a small condenser to a small microscope, what is the smallest condenser available?

Thanks

apochronaut
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Re: Improving a toy microscope..add a condenser?

#12 Post by apochronaut » Tue Feb 07, 2023 2:08 pm

There are small condensers that attach to the bottom of the stage. Many companies made them but since they are attached to the stage, they are not often seen for sale without the microscope. I have some made by Bausch and Lomb if you are interested. I also have a brand new small AO condenser in it's box. I think it is for a model 60 and .66 N.A.
There was also a very small abbe condenser made by AO for their early phase contrast systems. It is about an inch across. Again they are not often seen without the phase diaphragm unit that it was made for.
The question also becomes this. How much of a condenser do you need? Most toy microscopes, even those with exaggerated magnifications work at no more than about .50 N.A., since the resolution seems to plateau or even deteriorate after about 400X on the better models. That means that a simple single lens condenser would work as well as a more complex higher N.A. one. The better models of toy microscopes from the past, those that promised 900 or even 1200X magnification did have a single lens condenser in the stage aperture. Why don't you try the stage of one of those or take the condenser out and cement it into your stage?
There is also the issue of flare. A condenser from a larger microscope, even a small one will need a way of reducing the aperture, otherwise your low magnification objectives will be too bright and suffer from low contrast. Disc diaphragms are sometimes on the better toy scopes but they don't really do the job that well. If you have a condenser suitable to provide , as an example , .66 N.A. you may need an iris in order to stop it down to .15 or so, in order to get contrast at those low magnifications.

dolmadis
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Re: Improving a toy microscope..add a condenser?

#13 Post by dolmadis » Wed Feb 08, 2023 8:55 am

apochronaut wrote:
Tue Feb 07, 2023 2:08 pm
The better models of toy microscopes from the past, those that promised 900 or even 1200X magnification did have a single lens condenser in the stage aperture. Why don't you try the stage of one of those or take the condenser out and cement it into your stage?
That is a helpful idea. Assuming that you don't have one of those stages spare in the part box or the lens is stubborn to remove intact what sort of lens could you substitute please?

Thanks for your help. John

apochronaut
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Re: Improving a toy microscope..add a condenser?

#14 Post by apochronaut » Wed Feb 08, 2023 5:55 pm

A typical example is the cast aluminum stage supplied on the 1200X with fine focus made by Carton Optical. It is mostly seen as a Tasco. The stage has a plano/convex slightly over 1/2" single lens condenser, mounted from below with a snap ring.Since the microscope provides acceptable imaging up to 480X , that lens probably gives close to .50 N.A. The curvature is about that of the field lens of a 5 or 6X eyepiece. The lens itself is about 18mm in diameter and it covers a field of 3250 microns, which is what the microscope sees with it's 5X objective and 8X W.F. eyepiece. That's a F.N. of about 17.5, so it isn't too shabby for a toy microscope from 1965. The cast aluminum stage itself is 3 X 3 1/2 inches and is drilled at 1 1/2 " plus a locating pin for a mini XY slide carrier. Tasco supplied decent ones. Part # 1581. The stage weighs 3.8 oz. with clips and the carrier 4.4 oz. Those current mini Chinese ones will probably work too. There is a disc diaphragm.

It would be easy to use a lightly curved doublet from surplus as a condenser and it might provide a slight improvement in contrast. It's depth would interfere with any disc diaphragm but putting the lens in a short section of fitted pipe centered and glued to the underside of the stage would then allow for one of those cheap ebay irises in the bottom of the pipe.
Here is an acceptable doublet at silo.

https://www.ebay.com/itm/264285943074?h ... SweW5U6ifi

https://www.ebay.com/itm/255550302002?h ... BM7IL2osZh

dolmadis
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Re: Improving a toy microscope..add a condenser?

#15 Post by dolmadis » Wed Feb 08, 2023 7:55 pm

Thank you for the custom build suggestion with examples.

As I live in the UK the lens suggestion gets heaped up with extra taxes and heavy shipping costs.

When I go to look for an alternative lens, say 18 to 20mm dia looking at the listed item with the ruler in the photos, would the choice of focal length be critical ? I have found that there are a few FL's to choose from over quite a range.

Thanks again, John

MicroBob
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Re: Improving a toy microscope..add a condenser?

#16 Post by MicroBob » Wed Feb 08, 2023 8:41 pm

What you want is a lens that offers a light cone with a wide included angle, a lens of e.g. 20-35mm and quite fat in the middle with a short focal lenght.

apochronaut
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Re: Improving a toy microscope..add a condenser?

#17 Post by apochronaut » Wed Feb 08, 2023 11:46 pm

You have to reserve judgement some on the diameter of the lens because toy microscope stages are quite small and many have bosses cast underneath for substage devices. The Carton Optical stage for instance could accept a 20mm diameter lens maximum with a bit of light machining or filing but without that 14mm is ideal. A real condenser with a conical top lens will work. The doublet I linked to is about the maximum for a disc lens. Any larger and the boss that accepts the disc diaphragm central mounting screw gets in the way. It protrudes about 1/4 cm. down from the lower stage surface. I agree in principal that a wider lens is better because it has a wider reasonably well corrected zone.
The actual stage has to be looked at carefully prior to selecting the condenser or condenser lens.
Do you already have a toy microscope you are trying to convert or are you in the process of choosing one?

dolmadis
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Re: Improving a toy microscope..add a condenser?

#18 Post by dolmadis » Thu Feb 09, 2023 6:46 am

Thanks again. I have a Meopta Travelling which I would like to improve. I have seen the post and threads on the Meopta referred to here but it does not deal with the issue of adding a condenser. The Quekett link does show that one can be added but I cannot deduce enough detail which is described as DIY. So help welcomed. Best, John

apochronaut
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Re: Improving a toy microscope..add a condenser?

#19 Post by apochronaut » Thu Feb 09, 2023 1:51 pm

Not really a toy then but it still would benefit from a condenser since the objectives work at conventional N.A.s. I can't give you any practical information except that in your case I would look for a small abbe type condenser due to the necessity to achieve .65 N.A. You won't get that with a single lens or even doublet unless the curvature of the convex lens is extreme, which will then cause other problems.You would benefit from an iris too.

The thinking in my previous posts was related to a true toy microscope which seldom achieve over .50.

However, going back to the original idea of putting a doublet lens in the top and an iris in the bottom of a short length of pipe. This pair of doublets ships free from China. The Meopta looks to have a pretty clear space under stage. These lenses are 24mm diameter, so would do fine. The curvature is about at the limit of what you want. They would be more than .50. The selection of irises I linked to above has both 23 and 25mm, so take your pick. For £30 a piece of pipe and a container of epoxy, you have a condenser. An achromat condenser
.https://www.ebay.co.uk/itm/2pcs-24mm-Op ... ect=mobile

dolmadis
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Re: Improving a toy microscope..add a condenser?

#20 Post by dolmadis » Thu Feb 09, 2023 3:08 pm

Hi, Many thanks for your consideration of how to improve the Meopta Traveller microscope with a condenser.

There is a clear space between the stage and the mirror of 20mm. That should be enough room to put together the lens and small diameter thin diaphragm on a short tube.

I will go with the parts you kindly suggested and see how it goes.

Thanks again, John

apochronaut
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Re: Improving a toy microscope..add a condenser?

#21 Post by apochronaut » Thu Feb 09, 2023 4:54 pm

Note that the measurements on the iris diaphragms are a bit difficult to interpret. The diameter quoted appears to be the diameter of the clear aperture when wide open. Used with a 24mm diameter lens fitted into a short tube, you would want the 1.5-23mm iris, which is 37mm in diameter overall and 7.1mm thick. It should be so that it will nicely cement to the bottom of the tube, allowing easy access to the lever. I would want the iris as large as possible but not larger than the lens.
Based on the design of the iris units, it looks like there will be a decent lip beyond the 23mm opening for the tube to cement to.
Finding a tube might be a bit tricky. You need one not much bigger than 24mm i.d. but I am sure there are some out there . The iris spec. says 7.1mm deep, which might leave quite a bit of space above the leaves. It is possible that the lens might nestle nicely into the diaphragm frame above the leaves and could be carefully epoxied directly to it. Paint the edge of the lens black and cement the edges of the plano surface directly to the stage with a really good vibration resistant cement. Perhaps that black silicone stuff they do automotive gaskets with?

The seller does mention that custom sizes are available if ordered. Perhaps you could request that the 23mm iris be made a little deeper than 7.1 mm with a 24mm l diameter upper throat. That would integrate the tube to the iris assembly and you could then just insert and cement the lens flush with top?
Last edited by apochronaut on Thu Feb 09, 2023 5:40 pm, edited 1 time in total.

dolmadis
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Re: Improving a toy microscope..add a condenser?

#22 Post by dolmadis » Thu Feb 09, 2023 5:02 pm

All very thoughtful suggestions, thank you, because I am not a natural in the clutches of diy !!

Best, John

apochronaut
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Re: Improving a toy microscope..add a condenser?

#23 Post by apochronaut » Thu Feb 09, 2023 5:53 pm

I hope this all works. I would request perhaps a 10 mm total height. I don't know if a 24mm diameter i.d. at the top is possible but it is worth a try. At any rate, even if the customization is unavailable outside of the iris diameter, it looks like a 1.5mm-23mm x 7.1mm deep iris will work fine and the curvature of the lens should nicely nestle and cement into the upper aperture of the iris housing.

Even if the condenser is limited to .50 the resolution of your 40X objective will still be close to it's theoretical potential and the contrast be quite improved.

dolmadis
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Re: Improving a toy microscope..add a condenser?

#24 Post by dolmadis » Thu Feb 09, 2023 6:28 pm

Just digesting your thoughts.

The aperture in the stage is just over 11mm.

There is a circular indentation 3mm deep, 36mm dia, on the under surface of the stage centred on the aperture in the stage.

Shame not 38 mm but gives a little bit more space if the lens pops over the frame of the diaphragm.

It is very promising without the parts.

Best, John

Chas
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Re: Improving a toy microscope..add a condenser?

#25 Post by Chas » Thu Feb 09, 2023 7:34 pm

The standard Beck Abbe condenser is quite short ;
The head that contains the optics is 20mm top to bottom and it has quite a pointy snout (10mm diameter at the top) that would go into the stage.
The base containing the iris is the same kind of height.
When the optical head is mounted inside the iris/carrier the total height comes to around around 33mm.

I have noticed quite a few of these condensers mounted upside down in Beck microscopes, maybe you could also mount the optical head upside down,if you are very pushed for space,. The bottom of the optical head is~ 35.5 mm outside diameter.

Here is the head next to the screw top from a milk container:
Beck condenser head.jpg
Beck condenser head.jpg (28.73 KiB) Viewed 35013 times
Out of curiosity what is the highest magnification objective on the microscope ?

apochronaut
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Re: Improving a toy microscope..add a condenser?

#26 Post by apochronaut » Thu Feb 09, 2023 8:50 pm

Chas wrote:
Thu Feb 09, 2023 7:34 pm
The standard Beck Abbe condenser is quite short ;
The head that contains the optics is 20mm top to bottom and it has quite a pointy snout (10mm diameter at the top) that would go into the stage.
The base containing the iris is the same kind of height.
When the optical head is mounted inside the iris/carrier the total height comes to around around 33mm.

I have noticed quite a few of these condensers mounted upside down in Beck microscopes, maybe you could also mount the optical head upside down,if you are very pushed for space,. The bottom of the optical head is~ 35.5 mm outside diameter.

Here is the head next to the screw top from a milk container:

Beck condenser head.jpg

Out of curiosity what is the highest magnification objective on the microscope ?
Condense>>>condenser. Disperse>>>disperser. Upside down? Of what value is that as a condenser? If you turn the condenser upside down, why not turn the objective upside down as well?

Chas
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Re: Improving a toy microscope..add a condenser?

#27 Post by Chas » Thu Feb 09, 2023 10:03 pm

Upside down? Of what value is that as a condenser?
Not entirely sure.
I wouldnt have said that it was to avoid the objective clashing with the condenser's top as the Beck objectives of the period were short (and will not clash).
why not turn the objective upside down as well?
The objective lens in the Beck Binomax stereo magnifier is reversible (RMS threaded both sides); the lens sits 4cm from the RMS thread so by reversing the objective the optical tube length is altered by 8 cm :-)

dtsh
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Re: Improving a toy microscope..add a condenser?

#28 Post by dtsh » Thu Feb 09, 2023 10:51 pm

dolmadis wrote:
Thu Feb 09, 2023 5:02 pm
All very thoughtful suggestions, thank you, because I am not a natural in the clutches of diy !!

Best, John
Given that statement, why are you considering such? I've been known to do many foolhardy things for my own amusement or out of ignorance so I'm not trying to discourage anyone from an adventure, but if the desire is to end up with a decent instrument I would think a different instrument altogether would be the better path. You could install the finest of condensers and it's still going to be a mediocre instrument at best. If the goal is to get a condenser for the light gathering capabilities to make it a tad more useful for little to no money, I would be looking at glass balls from either the craft section or toy isle of my local shops.

Perhaps I am spoiled by the market in my country were an old monocular scope that's 60+ years old can be had for a pittance; I have had more than a few I've gifted to people because they're just so inexpensive. They're not especially light, but once you add the usual accoutrements of slides, coverslips, collecting jars, and whatnot the few extra lbs/kgs of an old instrument vs a plastic one doesn't seem to equate to much, but the quality difference between a nice old instrument and a toy would more than make up for it I would think.

apochronaut
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Re: Improving a toy microscope..add a condenser?

#29 Post by apochronaut » Fri Feb 10, 2023 12:10 am

Chas wrote:
Thu Feb 09, 2023 10:03 pm
Upside down? Of what value is that as a condenser?
Not entirely sure.
I wouldnt have said that it was to avoid the objective clashing with the condenser's top as the Beck objectives of the period were short (and will not clash).
why not turn the objective upside down as well?
The objective lens in the Beck Binomax stereo magnifier is reversible (RMS threaded both sides); the lens sits 4cm from the RMS thread so by reversing the objective the optical tube length is altered by 8 cm :-)
An upside down condenser will disperse the illumination field and lower the N.A. That might be useful for very low magnification objectives, which require a broad illumination field. Dolmadis seems to be trying to increase the N.A. of the illumination for a 200X magnification at .45 N.A. and possibly as well at 300X, which was the original set up of the Meopta AZ-2.

apochronaut
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Re: Improving a toy microscope..add a condenser?

#30 Post by apochronaut » Fri Feb 10, 2023 12:16 am

dtsh wrote:
Thu Feb 09, 2023 10:51 pm
dolmadis wrote:
Thu Feb 09, 2023 5:02 pm
All very thoughtful suggestions, thank you, because I am not a natural in the clutches of diy !!

Best, John
Given that statement, why are you considering such? I've been known to do many foolhardy things for my own amusement or out of ignorance so I'm not trying to discourage anyone from an adventure, but if the desire is to end up with a decent instrument I would think a different instrument altogether would be the better path. You could install the finest of condensers and it's still going to be a mediocre instrument at best. If the goal is to get a condenser for the light gathering capabilities to make it a tad more useful for little to no money, I would be looking at glass balls from either the craft section or toy isle of my local shops.

Perhaps I am spoiled by the market in my country were an old monocular scope that's 60+ years old can be had for a pittance; I have had more than a few I've gifted to people because they're just so inexpensive. They're not especially light, but once you add the usual accoutrements of slides, coverslips, collecting jars, and whatnot the few extra lbs/kgs of an old instrument vs a plastic one doesn't seem to equate to much, but the quality difference between a nice old instrument and a toy would more than make up for it I would think.
It is possible you have lost the movement of the thread. The original post was related to improving a toy microscope but Dolmadis is not trying to improve a toy microscope. He is trying to put a condenser on a quite good quality Meopta AZ-2 portable microscope, yet with only 20mm vertical space to do it in. The AZ-2 was not supplied with a condenser originally but at .45 N.A. , the high power objective it was fitted with would benefit some from a condenser. This microscope would be hard to replace cheaply with one of equivalent portability coupled to optical quality. The key here, is it's diminutive size yet with optical quality equivalent to a full size microscope.

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