Replace condenser with Abbe 1.25

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Marc
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Joined: Thu Mar 25, 2021 1:58 am

Replace condenser with Abbe 1.25

#1 Post by Marc » Thu Mar 25, 2021 2:29 am

Hi!

I have a humble 40x microscope like the image. It mounts a 0.6 condenser.

I'm thinking in replacing the condenser with one Abbe 1.25, in order to try the 100x oil objective.
I cannot spend too much money, although the 2 modifications buying chinese or second hand parts would be affordable to me.

Is this modification possible with this type of microscopes?. I would be grateful to read any help

Image

dtsh
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Re: Replace condenser with Abbe 1.25

#2 Post by dtsh » Thu Mar 25, 2021 12:32 pm

It's probably possible, but you might need to make a new mount to adapt the new condenser to the microscope's condenser mount. You might get lucky and find one that fits without much modification, but I wouldn't bet on it.
Some pictures and measurements of the current condenser and mount would be helpful.

PeteM
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Re: Replace condenser with Abbe 1.25

#3 Post by PeteM » Thu Mar 25, 2021 2:27 pm

Depending upon the used market where you are located, it might be you can find an entire microscope for about the same cost as a new Chinese condenser or one bought from Ebay? Keep and eye out, now that you know what you want. You might find an old microscope with a binocular head, an Abbe 1.25 condenser, and x-y mechanical stage, four or five objectives, etc. for under $50.

A phone camera adapter on your current microscope might make it a good instrument for taking photos, bringing along on trips, etc.

Marc
Posts: 32
Joined: Thu Mar 25, 2021 1:58 am

Re: Replace condenser with Abbe 1.25

#4 Post by Marc » Thu Mar 25, 2021 5:16 pm

sounds good, thanks for the help!. Hope I can do it.

I cannot find used microscopes with Abbe 1.25 with a good price. Although I have find both the 100x objective and Abbe condenser and this is affordable to me.
My doubt is about some optic incompatibility by design. If the problems are only about screws and similar adaptations then no fear ;)

This is my microscope with one image of the condenser part.
IMG2.jpg
IMG2.jpg (92.84 KiB) Viewed 4870 times
IMG1.jpg
IMG1.jpg (74.44 KiB) Viewed 4870 times
Diameter is 50 mm for the circle of the 3 condenser screws. I have found Abbe condensers in that size then I suspect not many problems with this.

Image


However, my main doubt is with the microscope plate. I have seen many microscopes mouting 1.25 Abbe condensers these have a plate with more thickness, like this:

Image

these plates can have 150 mm thickness and more. Mine is only 100 mm.

I wonder if maybe the reason is the upper protuberance in the 1.25 Abbe condenser, which can force to use a thicker plate. This:

Image

Do you think the thickness could be bypassed with some adaptation to separate the condenser, without affecting light optics?


In short, these are my main doubts:

- the possible optical incompatibilities by optical design to mount a new Abbe 1.25. If it doesn't exits, good news!.
- the thickness of the existing plate. I have searched to find cheap thicker plates although this part seem to be absent in chinese and second hand maket.


any advice or idea would be helpful

dtsh
Posts: 977
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Re: Replace condenser with Abbe 1.25

#5 Post by dtsh » Thu Mar 25, 2021 7:23 pm

I presumed it had at least an adjustable condenser; still, nothing is impossible, but it might be less effort and expense finding another scope which has one.
Right at this moment it seems the prices on average have gone up, but I suspect in few weeks they will be back to more typical amounts.

What continent are you presently on and what kind of budget do you have?
There's a lot one can do if you're the creative sort, then it's largely a matter of time if all other options are not available.
Any access to a 3D printer? There are other ways, but that would probably be your fastest way of adapting something.

apochronaut
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Re: Replace condenser with Abbe 1.25

#6 Post by apochronaut » Thu Mar 25, 2021 8:00 pm

The thickness of the plate does not matter. The most important detail is where the top lens sits. It needs to be just below the slide, so it csn be oiled to the slide....about 1mm. In order to use the condenser at 1.25 N.A. it must be oiled to the slide. If it is not, then it will work at about .90 N.A., still o.k. for use with a 1.25 N.A. objective.
An abbe condenser like that, will not likely provide an illumination circle big enough to fill the field of low power objectives, such as your 4X. Your current condenser will. The way a 1.25 abbe is used in order to fill a low power field can vary. 1) rack the condenser down, which increases the field size. You won't be able to do that with it fixed to the stage. 2) Remove the condenser. Easy to do with a substage fork but cumbersome if it is screwed to the stage.3) Remove the top element to lower it's N.A. and widen the field. Again not possible. 4) Connect an auxiliary lens underneath that can be swung into the light path, lowering the N.A. and widening the field.

Number 4 is your only option. You will need to make sure that you get a condenser with a swing out filter tray like the one you are showing. You can then buy a correct size plano convex lens, to fit the carrer surplus, from one of the surplus dealers....usually about 10.00 plus shipping. Epoxy the lens into the filter carrier. Just a tiny bit on the edges is enough. You will need to make sure there is an accurate stop, so the lens achieves alignment with the condenser . Just a screw will do if you can get it accurate but that is hard. A post with a horizontal adjustment screw is good.
Last edited by apochronaut on Thu Mar 25, 2021 8:51 pm, edited 1 time in total.

MicroBob
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Re: Replace condenser with Abbe 1.25

#7 Post by MicroBob » Thu Mar 25, 2021 8:13 pm

Hi Marc,
condensers have different focus points: Some expect the light source in the foot of the microscope, some in infinity, and very few at the place where your light source is. The condenser would need half way proper centration, so to get good performance you better build a centration system for the condenser.
The objectives of your microscope look a bit toy like, not one of the common systems. This will make it more difficult to find an objective that will be parfocal with the other ones. If you are handy with tools a used good microscope might be a very good option and better use of your limited funds. But of cause there are areas where used microscope are hard to come by.

Bob

Marc
Posts: 32
Joined: Thu Mar 25, 2021 1:58 am

Re: Replace condenser with Abbe 1.25

#8 Post by Marc » Thu Mar 25, 2021 9:39 pm

dtsh wrote:
Thu Mar 25, 2021 7:23 pm
I presumed it had at least an adjustable condenser; still, nothing is impossible, but it might be less effort and expense finding another scope which has one.
these changes would be less than 50€ while microscopes 100x are around 250€-400€. Not directly a problem to spend more money (despite this is quite money) but just I'm newbie in microscopy. My initial thought was to take profit of this old microscope adding some option to try 100x oil immersion despite not a good optical quality. And if time later I check I'm more engaged, then I could think in a good one.
Anyway the process of searching parts and informations has been quite useful to me.

MicroBob wrote:
Thu Mar 25, 2021 8:13 pm
condensers have different focus points: Some expect the light source in the foot of the microscope, some in infinity, and very few at the place where your light source is. The condenser would need half way proper centration, so to get good performance you better build a centration system for the condenser.
yes.. I'm reading the comments and I'm realizing the upgrade of some parts in an isolated way can be a wrong idea

apochronaut wrote:
Thu Mar 25, 2021 8:00 pm
Number 4 is your only option. You will need to make sure that you get a condenser with a swing out filter tray like the one you are showing. You can then buy a correct size plano convex lens, to fit the carrer surplus, from one of the surplus dealers....usually about 10.00 plus shipping. Epoxy the lens into the filter carrier. Just a tiny bit on the edges is enough. You will need to make sure there is an accurate stop, so the lens achieves alignment with the condenser . Just a screw will do if you can get it accurate but that is hard. A post with a horizontal adjustment screw is good.
thanks so much for this information. It sounds harder of what I believed, although very useful read this before buying replacements.

I already thought in not getting high quality in the final result, although from what I read It seems the mechanics and image could be affected in a serious way if there is no a precise result in the process you explain.


Thanks all for your valuable help :)

dtsh
Posts: 977
Joined: Wed May 01, 2019 6:06 pm
Location: Wisconsin

Re: Replace condenser with Abbe 1.25

#9 Post by dtsh » Fri Mar 26, 2021 2:21 am

Marc wrote:
Thu Mar 25, 2021 9:39 pm
dtsh wrote:
Thu Mar 25, 2021 7:23 pm
I presumed it had at least an adjustable condenser; still, nothing is impossible, but it might be less effort and expense finding another scope which has one.
these changes would be less than 50€ while microscopes 100x are around 250€-400€. Not directly a problem to spend more money (despite this is quite money) but just I'm newbie in microscopy. My initial thought was to take profit of this old microscope adding some option to try 100x oil immersion despite not a good optical quality. And if time later I check I'm more engaged, then I could think in a good one.
Anyway the process of searching parts and informations has been quite useful to me.
My advice would be to enjoy it as the instrument it is, put some cash aside and keep your eyes open for something with more features and options. I suspect you will spend more getting this where you want it than you would buying a complete replacement.

If you want to pursue modifying this one, I would start by measuring the thread diameter of the objectives you have now to see what they're compatible with. Do you have a pair of calipers, a micrometer, or a fine ruler (and good eyes)?

Marc
Posts: 32
Joined: Thu Mar 25, 2021 1:58 am

Re: Replace condenser with Abbe 1.25

#10 Post by Marc » Thu Apr 15, 2021 8:20 pm

finally I have followed the advices here and I bought a decent new microscope under a good discount. It has Abbe 1.25 and semi-plan objectives 10,20,40,100(oil inm).
I believe the reason for the discount was the halogen light, which today I don't care.

Now I should start another headache to find a camera :lol:

thanks for the help

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