How interchangeable are condensers?

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farnsy
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How interchangeable are condensers?

#1 Post by farnsy » Tue Jun 22, 2021 8:11 pm

Aside from the physical compatibility (right size of dovetail), are there any other considerations when using a condenser that was made for a different microscope? For example, assuming I can make the dovetail work, is it just fine to use an achromat/aplanat 1.4 condenser made for 160mm Olympus or an older American Optical system on a current Nikon infinite system or vice versa? Is optical system compatibility or light-source compatibility a thing when looking at condensers?

I have a new microscope that has high-performance objectives but the manufacturer does not make any high-performance condensers (only abbe and flip-out), so I'm looking around at condenser options and I want to make sure there is nothing I am missing.

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Re: How interchangeable are condensers?

#2 Post by PeteM » Tue Jun 22, 2021 9:11 pm

Nikon finite condensers (Labophot/Optiphot) will fit on Olympus BH2, center, and provide compatible optics. The Olympus BH2 dovetail is about 1mm larger, but can be made to fit if there's a reason to do a swap the other way.

There's no guarantee that other condenser swaps will work even if you manage a connection, since the combination of lamp to field lens optics and condenser optics might not be compatible. Even trickier if you hope to cover very low power objectives (4x and under) or hope to have the spacing just right to get Kohler illumination and have the top of the condenser oiled to the bottom of the slide.

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75RR
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Re: How interchangeable are condensers?

#3 Post by 75RR » Tue Jun 22, 2021 9:57 pm

farnsy wrote:
Tue Jun 22, 2021 8:11 pm
I have a new microscope that has high-performance objectives but the manufacturer does not make any high-performance condensers (only abbe and flip-out), so I'm looking around at condenser options and I want to make sure there is nothing I am missing.
Curious as to which new microscope and what high-performance objectives you are referring to.

One of the reasons that the major manufacturers modular older finite microscopes are highly regarded, apart from the build quality and their better value for money,

is that they have a wide range of upgrades available - all designed to work seamlessly within the system.

As you have surmised, High-performance objectives require High-performance condensers - have you considered getting for example an Olympus BH2?
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

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Re: How interchangeable are condensers?

#4 Post by apochronaut » Tue Jun 22, 2021 10:11 pm

The front lens of a condenser is actually the bottom lens. The focal point of the condenser will be either finite or infinite, just like with objectives. Condensers from the past, when there was a mirror and a remote lamp were usually infinity corrected. As the illuminator became housed in the base and sometimes right under the stage more of them were designed to a finite focus.
It is the finite focus types that can present problems of incompatibility, usually due to them having to receive a cone of light of an incorrect diameter.

Many microscopes still have infinity corrected condensers, especially larger stands that have a distant filament and a more sophisticated collimation system.

If you can be sure that both the donor and patient scope both have infinity corrected illumination systems then a swap is possible as long as a fit can be made. The back(top) lens doesn't matter so much once the front focal plane is established because they are all intended to focus at a standard working distance and slide thickness.

With a finitely corrected condenser, the focal length could be determined and compared to the intended host stands illumination system.

With regards to your scope farnsy, I think the intent of the planfluor objectives was DIC, so the DIC condenser is probably a 1.4 achromat, is it not? That is my resding of it. They weren't thinking that too many customers would opt for the planfluor or planapos outdide of the DIC application.

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Re: How interchangeable are condensers?

#5 Post by farnsy » Tue Jun 22, 2021 10:39 pm

75RR wrote:
Tue Jun 22, 2021 9:57 pm
Curious as to which new microscope and what high-performance objectives you are referring to.
I am currently testing the hypothesis that the Chinese do, in fact, make good quality higher-end microscopes, you just have to pay for them. I will provide a review of the system to the whole forum soon, after I've done some more testing.

In short, my new microscopes is a BestScope BS2081. It is built in the same factory as the Nikon products Novel Optics manufactures, so their optical system is compatible with Nikon's current system (60mm parfocal, 200 reference, etc.). It is essentially the same microscope sold as AccuScope EXC-500, Nexcope NE900, Radical RXLr-5, and EuroMex Delphi Observer and is closely related to Nikon's E200/E400/E600 line and the current Ci line.

Novel doesn't make all of Nikon's objectives, but they do apparently make some. I'm using fluorite and apo objectives along with their DIC and phase contrast systems. So far I'm very happy with all of it optically and mechanically--only very small downsides, mostly with the buying process. Anyway, they don't sell any achromat/aplanat condensers. There's a good chance the Nikon 1.4 achromat/aplanat condenser will fit in my yoke, but that I'm not certain and looking at all my options since that condenser is not cheap. Optimally I'd like to add an achromat/aplanat optical top to the phase and DIC condensers they supplied, but that involves a little more than finding a fitting yoke (the threads have to fit exactly and I could imagine geometric/optical issues with that as well).
Last edited by farnsy on Tue Jun 22, 2021 11:37 pm, edited 2 times in total.

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Re: How interchangeable are condensers?

#6 Post by farnsy » Tue Jun 22, 2021 10:56 pm

apochronaut wrote:
Tue Jun 22, 2021 10:11 pm
With regards to your scope farnsy, I think the intent of the planfluor objectives was DIC, so the DIC condenser is probably a 1.4 achromat, is it not? That is my resding of it. They weren't thinking that too many customers would opt for the planfluor or planapos outdide of the DIC application.
Thanks, as always, Apo. That was some new and very useful information.

My scope and phase system are here, but I have not yet gotten the DIC components, so I can't examine or test the DIC condenser directly yet. However, I did email them about this and they said that all their condensers, including the DIC and phase condensers, are not achromat/aplanat. The person I talked with was primarily in sales and not a technical person. She has made a few mistakes as we were discussing things, but I got the feeling she asked someone before replying to that email.

How would I test these condensers myself? Would I look at the field diaphragm and see if there are blue/yellow fringes at the edges of it? Or is there a better way?

Does anyone happen to know if Nikon's current Eclipse Ci condenser system is infinite? Actually, I need to make some measurements. They may have gone with an Olympus-sized yoke since so many Chinese products are intended to be kind of Olympus-compatible.

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Re: How interchangeable are condensers?

#7 Post by apochronaut » Tue Jun 22, 2021 11:49 pm

You are correct. I just looked at the brochure. The DIC condenser says 1.25 on it. It is possibly an abbe aspheric? That would make some difference but presumably, they have done their homework.
I have seen instances where a wider field condenser, with greater diameter lenses, outperforms it's type because the sweet spot of the condenser is broader, with a wider zone of near axial correction. PZO used a broader lens abbe condenser for their DIC to excellent effect. When you get it, you can determine the thread on the condenser. There may be one very close that could be modified to thread in there to get your N.A. up there for BF. Your 1.4 planfluor will perform slightly better at a :ugeek: higher aperture.

The Eclipse D-CUO 1.4 DIC condenser is 2800.00. ....just the condenser.

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Re: How interchangeable are condensers?

#8 Post by farnsy » Wed Jun 23, 2021 12:07 am

apochronaut wrote:
Tue Jun 22, 2021 11:49 pm
The Eclipse D-CUO 1.4 DIC condenser is 2800.00. ....just the condenser.
Yeah, that's a pretty good reason to do some research on fitting condensers from other manufacturers or older models!

By the way, I opted for the water immersion 100X (NA=1.1), not the 1.4 fluor oil. So the difference between 1.25 and 1.4 may not be as critical at this time. However, I may change my mind about that in the future.

BTW, here's what BestScope said, for reference, when I asked about their four condensers (abbe, flip-top, phase, and DIC).
Our Universal Condenser and swing out condenser are normal Abbe condenser,Achromatic or aplanatic is higher level condenser, Normally,their NA Value is 1.4.
Our condenser isn’t this kind.We supply these two kinds because the failure rate of Universal condenser is much lower.
It mainly be used on Motorized Microscope.Relatively speaking,The result of the swing out condenser is better,
especially when using 2X and 4X objectives,The brightness in the field of view is more uniform.
DIC and phase condensers should not be achromatic or aplanatic.
Any info on how to test condensers or how to know if they are finite or infinite would be much appreciated.

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Re: How interchangeable are condensers?

#9 Post by apochronaut » Wed Jun 23, 2021 1:01 am

If you take a bright flashlight with a homogeneous glass or lens( those lumpy ones with the multiple leds are o.k. too but they remind me of melted flashlights) and put it right at the back( top )lens, and then directing the beam out the front lens, move the condenser in and out relative to a flat surface. An infinity corrected condenser will project a broad glow about 2 feet across when the condenser is roughly 16" from the surface. Your light source is uncollimated, highly divergent, so there will be a dispersed glow. Inside that broad glow there will be a brighter core, representative of the portion of the beam being collimated by the condenser. That core will be more difficult to see with distance from the target surface. As you move the condenser closer to the surface the core will get brighter and more defined from the general glow. The diameter of the illuminated field will in general shrink as you move the condenser closer to the surface and near proximity, that central spot will be about the size of the condenser aperture. Make sure your iris is wide open.

If you turn the condenser around and shine the light from the front( bottom) lens and perform the same procedure, you will find that the condenser will focus the light to a very small spot very close to the surface; within mm. That is it's focus at the object plane.

A distance corrected condenser when subjected to the same procedure as in the first example will also focus the light at a fixed distance down to a focused small disc but not necessarily exactly at it's focal distance, unless your light source emanates from the plane of it's back focal distance or the object plane.

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Re: How interchangeable are condensers?

#10 Post by farnsy » Wed Jun 23, 2021 1:29 am

Sounds like I have some fun experiments to run tonight.

Also found some more information and experiments here. That link also seems to suggest that cheap abbe type condensers tend to be infinity corrected, while the expensive aplanatic/achromatic ones tend to have a finite focus. Interesting.

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Re: How interchangeable are condensers?

#11 Post by apochronaut » Wed Jun 23, 2021 1:50 am

That would make sense if it had the prefix non attached. Both abbe and achromats are used in the same microscope with the same illumination system as optional choices. How could one be infinity and the other fixed focus?

I have seen instances where a condenser is used in two different models of closely related microscopes fitted with different illumination systems. In some of those cases there is an auxiliary lens that can be installed under the front condenser lens to either change it's front focal distance or change it from fixed to infinity.

Something that maybe needs to be noted is that the terms fixed and infinity in this context have nothing to do with the optical system of the microscope. It is strictly the condenser that is fixed or infinity and an infinity corrected microscope can have a fixed distance condenser and as was often the case, a fixed tube microscope can have an infinity corrected condenser.

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Re: How interchangeable are condensers?

#12 Post by farnsy » Wed Jun 23, 2021 2:16 am

apochronaut wrote:
Wed Jun 23, 2021 1:50 am
That would make sense if it had the prefix non attached.
Can you help me understand what a prefix is in this context?

To make sure I'm following correctly, I would imagine that a microscope with a built-in illuminator and with an infinity focused condenser would require a lens within the microscope body that is analogous to a telan lens. Is that right?

[filament] -> [lens in question] -> [field diaphragm] -> [ collector lens] -> [condenser]

Am I way off on that? Or does the collector lens serve that purpose?

I think I need to get set straight here.

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Re: How interchangeable are condensers?

#13 Post by apochronaut » Wed Jun 23, 2021 2:50 am

That was just a smartass roundabout way of saying it sounds like nonsense. Where did that reference come from? I can't see how a blanket statement that cheap abbe are more likely to be infinity and achromats are more likely finite makes any sense at all. Both are used on the same microscopes, so if designed as options for a specific microscope they both will be one or the other, depending on the microscope not the condenser design.
I could see that some company might have an existing older abbe design that might be infinity and rather than redesign the entire condenser in order to fit it into a small footprint microscope with a short illumination pathway, they might just adapt it with an aux. optic......and then an achromat might be designed to spec with a fixed focal length for the same scope.

Regarding the telan lens.

Since the condenser is a reversed objective, or a mirror image of the objective; in fact the best condenser being the identical objective mounted upside down substage, the telan lens is the collimater.It just functions in reverse. It converts the diverging beam from the filament into a parallel bundle, instead of converting the parallel bundle to a converging beam.

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Re: How interchangeable are condensers?

#14 Post by farnsy » Wed Jun 23, 2021 3:24 am

apochronaut wrote:
Wed Jun 23, 2021 2:50 am
That was just a smartass roundabout way of saying it sounds like nonsense. Where did that reference come from? I can't see how a blanket statement that cheap abbe are more likely to be infinity and achromats are more likely finite makes any sense at all. Both are used on the same microscopes, so if designed as options for a specific microscope they both will be one or the other, depending on the microscope not the condenser design.
I could see that some company might have an existing older abbe design that might be infinity and rather than redesign the entire condenser in order to fit it into a small footprint microscope with a short illumination pathway, they might just adapt it with an aux. optic......and then an achromat might be designed to spec with a fixed focal length for the same scope.
Yeah, I think I didn't really summarize what he said well and probably straight-up misrepresented it--it is pretty easy for someone unfamiliar with this stuff to take perfectly reasonable statements and transform them to nonsense. This is from the link
from above:
Manufacturers happen to have marketed two different types of condensers, unfortunately without specifically saying which type it is by engraving it on the condenser. The first is “corrected for infinity”: it’s so designed that spherical correction is best if the light source is at an infinite distance from the condenser. One (front) aplanatic point is thus at infinity, the other lies at the natural (rear) focus of the condenser. Simple (“uncorrected”) condensers sometimes (and quite erroneously) called “Abbe-type” condensers of vintage microscopes - but also much later - fall in this category.

The second is corrected for a much smaller distance of the light source, typically 35 cm or so. This is not unreasonable because the illuminator will be placed on the bench, or is built into the microscope. The front aplanatic point will then be at about 35 cm. Typical examples are found among modern highly corrected condensers.
Based on what you say above, it sounds like infinite (condenser) systems would either have an exterior light source or it would have a collimating lens somewhere before the condenser, potentially using the lamp collector for this purpose. Right?

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Re: How interchangeable are condensers?

#15 Post by hans » Wed Jun 23, 2021 4:17 am

I have seen the analog of tube lens on the illumination side called either the collimating or field lens depending on manufacturer. It collimates (images at infinity) the field iris, not necessarily the actual illumination source. The image of the field iris at infinity is then focused into the specimen plane by the condenser. There was some discussion of the AO/Reichert systems both finite and infinite in this thread:
https://www.microbehunter.com/microscop ... =5&t=10709

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Re: How interchangeable are condensers?

#16 Post by hans » Wed Jun 23, 2021 5:04 am

Oh and I also have some doubts about that article, was asking a few months ago if anyone knew of other sources:
https://www.microbehunter.com/microscop ... =5&t=12402

Still curious and haven't made much further progress understanding the subtleties myself.

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Re: How interchangeable are condensers?

#17 Post by MicroBob » Wed Jun 23, 2021 10:05 am

Hi together,
on a Zeiss Standard microscope there are different options to use the same infinity condensors, some not obvious:
1. By means of a swing in aux lens
2. By means of a different swing in lens on a different stand
3. By means of a screwed in aux lens on stands without swing in lens
4. Without aux lens on a Phomi or Universal 1 but only for the higher magnifications
5. Probably a few more for inverted microscopes etc....

So there are perfect options to mess things up by mixing components that nearly fit. :roll:

I think that not many people are aware of the condenser correction options so I can imagine that condensers are not always labeled as detailed as objectives. For Zeiss I have n.a. 1.4 bright field condensers, one apl. the other achr. apl.. I can't see a difference, they seem to be identical. Especially for lower power condensers it is probably easy to design a semi achr. apl low cost easy to use version that would be well regared by the average user.

So back to the question: It might be necessary to find the right aux lens when adapting condensers from other systems.

Bob

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Re: How interchangeable are condensers?

#18 Post by apochronaut » Wed Jun 23, 2021 11:07 am

Due to the precision of the image of the filament or field iris not being as important as the precision of the image of the specimen. Condensers are fairly crude when compared to objectives. That's why an identical objective works the best as a condenser.

If the 1.4 apl. and 1.4 achromat aplanat are different , that should be evident in the design of the elements.

Many people have tried to use the uv mirror objectives, thinking that they would be ca free and therefore like an apo. Well they are but they don't work with a standard condenser very well. I get a lot of flare and contrast reduction. B & L sold the objectives in a set along with a mirror condenser, which looks to be identical only modified to fit the condenser mount. Whether the innards are identical I don't know but it is a mirror condenser with the same N.A. as the objective.

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Re: How interchangeable are condensers?

#19 Post by hans » Thu Jun 24, 2021 2:07 am

MicroBob wrote:
Wed Jun 23, 2021 10:05 am
...on a Zeiss Standard microscope there are different options to use the same infinity condensors, some not obvious... [various aux lens configurations]
Are all the condensers infinity-corrected and the aux lenses always positive? Or are there also cases where finite condensers are used in infinity systems with negative aux lenses?

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Re: How interchangeable are condensers?

#20 Post by MicroBob » Thu Jun 24, 2021 5:32 am

Hi Hans,
the Zeiss Standard condensers I know areall infinity and used with a collecting auxillary lens of different focal lenths. Sometimes condenser and aux lens form a unit, screwed together. There may be systems with finite condenser design and negative aux lens, but I think there are few reasons to design it this way.

Bob

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Re: How interchangeable are condensers?

#21 Post by benjamind2021 » Tue Jul 20, 2021 9:58 pm

farnsy wrote:
Tue Jun 22, 2021 10:39 pm
In short, my new microscopes is a BestScope BS2081. It is built in the same factory as the Nikon products Novel Optics manufactures, so their optical system is compatible with Nikon's current system (60mm parfocal, 200 reference, etc.). It is essentially the same microscope sold as AccuScope EXC-500, Nexcope NE900, Radical RXLr-5, and EuroMex Delphi Observer and is closely related to Nikon's E200/E400/E600 line and the current Ci line.
I'm really interested in the BS2081 but alas cannot find it in Australia. I am a bit worried about international shipping with the COVID and the risks of loss and customs duties.

It would be wonderful if someone in Australia could order one in. It seems like a great budget DIC setup. I've always been interested in DIC and if the quality is really good then it would be worthwhile. I saw it on Alibaba with a price of maximum $10k AUD presumably this would be the DIC setup. Much better than spending $30k on any of the big 4 manufacturers.

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Re: How interchangeable are condensers?

#22 Post by farnsy » Wed Jul 21, 2021 12:10 am

benjamind2021 wrote:
Tue Jul 20, 2021 9:58 pm
I'm really interested in the BS2081 but alas cannot find it in Australia. I am a bit worried about international shipping with the COVID and the risks of loss and customs duties.

It would be wonderful if someone in Australia could order one in. It seems like a great budget DIC setup. I've always been interested in DIC and if the quality is really good then it would be worthwhile. I saw it on Alibaba with a price of maximum $10k AUD presumably this would be the DIC setup. Much better than spending $30k on any of the big 4 manufacturers.
Bestscope does sell through alibaba. That's how I bought mine.

The same scope (pretty much) is also sold as Nexcope E900 or NE900, AccuScope EXC-500, Euromex Delphi Observer, labomed LB-286, and Radical RXLr-5. I'm not sure which of those brands would have the DIC kit, but you might be able to find it somewhere and ask about DIC. I don't know what tariffs look like for you in Australia. Under normal circumstances there are no tariffs to the US for microscopes, but due to the trade war there's a 25% one from China. Ouch! Also DHL shipping was $500. But it might be cheaper to Australia. I don't think there's much worry about it getting lost in the mail if you buy through Alibaba. They use top shelf shippers that fly it right to you in a few days. That's why shipping costs so much.

They did take a couple of months to manufacture it before sending it over. Be prepared for that, especially if you do a lot of customizations. That's pretty normal even from the big 4 manufacturers, though. Bestscope has some things that are a little bit special, like septuple nosepiece and a 20X apo objective. Note that you can't have both of these at the same time because the apo objective is too fat to allow adjacent objectives if you get the septuple nosepiece. I bought the 20X apo but it doesn't seem to work as well with DIC as the other objectives do. If I had it to do over, I might have just stuck with fluor objectives. They are a bit more vetted.

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Re: How interchangeable are condensers?

#23 Post by benjamind2021 » Fri Jul 23, 2021 10:44 am

farnsy wrote:
Wed Jul 21, 2021 12:10 am
If I had it to do over, I might have just stuck with fluor objectives. They are a bit more vetted.
Sounds great. I think fluor objectives are good enough for DIC and most microscopy work.

Do you have any DIC images created through the BS2081?

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Re: How interchangeable are condensers?

#24 Post by farnsy » Fri Jul 23, 2021 7:56 pm

I don't have any DIC images from this scope yet...I haven't 100% figured out my camera solution.

Today or tomorrow I'll do a video review of my scope and start a thread on it in the "my microscope" forum. We can discuss the ins and outs there and I'll see if I can get some sample images as well.

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Re: How interchangeable are condensers?

#25 Post by benjamind2021 » Fri Jul 23, 2021 10:26 pm

farnsy wrote:
Fri Jul 23, 2021 7:56 pm
I don't have any DIC images from this scope yet...I haven't 100% figured out my camera solution.

Today or tomorrow I'll do a video review of my scope and start a thread on it in the "my microscope" forum. We can discuss the ins and outs there and I'll see if I can get some sample images as well.
That would be fantastic! It's great that there is now a DIC microscope available for those with a more modest budget. Having seen some amazing images from new Nikon DIC setups, this will be very interesting.

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Re: How interchangeable are condensers?

#26 Post by Kenskid » Wed Sep 07, 2022 1:04 am

Hello. I have this condenser. Nikon universal achr-apl con.a 1.4

10, 20, 40x all are perfect. 4x however does not fill the ocular moving condenser all the way down gets it close.

The 4x is not PLAN. The others are. Is this the reason for my delema?

Thanks

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Re: How interchangeable are condensers?

#27 Post by apochronaut » Wed Sep 07, 2022 2:41 am

No. Condensers have a field of view, just like objectives. The higher the condenser N.A., the narrower the field of view usually but wide field high N.A. condensers have been and are built but they are low production and therefore usually expensive.

Your condenser has a narrower field of view than your 4X objective, so is not filling the image circle with light. Most condensers have aux. lenses available to de-condense the illumination for the low power wider field objectives.

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Re: How interchangeable are condensers?

#28 Post by dtsh » Wed Sep 07, 2022 3:00 am

Someone correct me if I'm wrong, but a short focal length planoconvex lens like you would see for an aux lens mounted at the bottom of the condenser (plano toward condenser, convex toward light source) should correct that, yes?

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Re: How interchangeable are condensers?

#29 Post by Greg Howald » Wed Sep 07, 2022 4:01 am

Yes. But finding the right lens may be difficult I sometimes wonder if the people who make lenses for spectacles might be able to help in that regard but I have never asked .

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Re: How interchangeable are condensers?

#30 Post by zzffnn » Wed Sep 07, 2022 4:32 am

Kenskid wrote:
Wed Sep 07, 2022 1:04 am
Hello. I have this condenser. Nikon universal achr-apl con.a 1.4

10, 20, 40x all are perfect. 4x however does not fill the ocular moving condenser all the way down gets it close.

The 4x is not PLAN. The others are. Is this the reason for my delema?

Thanks
That kind of condenser can usually fill 4x onective, if you screw off the condenser top lens. If you don't pixel peep for critical high resolution work, you can simply use 4x without condenser.

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