Condensers - venting frustration

Do you have any microscopy questions, which you are afraid to ask? This is your place.
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Maryfox
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Condensers - venting frustration

#1 Post by Maryfox » Sun Jun 14, 2020 1:53 pm

As a rank beginner, it has not been easy to learn about condensers. My student scope did not have one. My big excitement about having a condenser on my new scope was because it has a filter holder. I wanted to learn about how to use it.

My internet searches brought up all kinds of technical information with diagrams of a condenser’s construction, and about cones of light. Somewhat interesting but at this stage of my learning curve, I don’t care about technical details. Maybe later, when I’ve learned more.

I am interested now only in how to get the best images. I finally got useful information from a December, 2008 Microbe Hunter Magazine article. At last!

I wish that knowledgeable people would take pity on those of us who start out with very basic equipment. Please, someone publish online a “Condensers for Dummies”. Or maybe I’m the only dummy.

Mary

Mraster2
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Re: Condensers - venting frustration

#2 Post by Mraster2 » Sun Jun 14, 2020 2:19 pm

Maryfox wrote:
Sun Jun 14, 2020 1:53 pm
I finally got useful information from a December, 2008 Microbe Hunter Magazine article. At last!

Please, someone publish online a “Condensers for Dummies”. Or maybe I’m the only dummy.
Sounds very interesting (I'm having issues with my condenser and illuminating it) but,
Me=dummy also because I cant find that issue ! Earliest I can find is Volume 1, Number 1, January 2011

Have you a link please ?

Hobbyst46
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Re: Condensers - venting frustration

#3 Post by Hobbyst46 » Sun Jun 14, 2020 2:28 pm

A photo of your microscope, close up photos of the microscope condenser, and of the objective markings (NA, phase contrast or not), and answers to below questions:
1. Does the microscope have a field aperture ? does it provide Kohler illumination ? (should be mentioned in the instruction manual - but if it is a used scope and we know the model, it might be known antway);
2. Can the condenser be moved up and down on a rack ?
Might help us to provide specific suggestions as to how to optimally use it.
Last edited by Hobbyst46 on Sun Jun 14, 2020 2:29 pm, edited 1 time in total.
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MicroBob
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Re: Condensers - venting frustration

#4 Post by MicroBob » Sun Jun 14, 2020 2:29 pm

Hi Mary,
microscope technique is not a simple thing. While it is possible to give very simple instructions on how to use the condenser it will help you only so far, because you don't know the reason for the given settings and can't adjust them to other situations by yourself. A bit like not wanting to know the map of your home town. One could explain the distances and turns to the super market, but you would never find the post office yourself.

It is good your new microscope has a condenser, magnifications above 100x give a much better image.
Different condensers support different objectives, like 10:1 and above or 2,5:1 to 40:1 but not more. Can you post a picture of your condenser? Does it have a removable top lens? Is it possible to center it? Does your microscope have a field lens?

Usually the starting point is condenser nearly in top position, condenser aperture full open, then close it until an effect just becomes visible.

Bob

MichaelG.
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Re: Condensers - venting frustration

#5 Post by MichaelG. » Sun Jun 14, 2020 2:31 pm

This might be a good place to start, Mary
https://olympus.magnet.fsu.edu/primer/a ... nsers.html

The interactive tutorials are a big help

MichaelG.
Too many 'projects'

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Maryfox
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Re: Condensers - venting frustration

#6 Post by Maryfox » Sun Jun 14, 2020 8:16 pm

Mraster 2 -
On the Microbe Hunter home page I searched for "condenser" and got 2 hits

What does the condenser do? http://www.microbehunter.com/what-does- ... denser-do/ Just a single paragraph

Working with the condenser aperture diaphragm http://www.microbehunter.com/working-wi ... diaphragm/

Hobbyist 46 - MicroBob-
Field Aperture??? Kohler illumination??? Both above my grade level (rank beginner). I'll get there, but not yet. My Celestron CB200CF came with a user's manual that is all of 14 pages that repeats the same information in English plus 5 more languages.

I must have at least some user basic information on how to use it before I can make sense of the more technical stuff.

MichaelG -
Thanks for the link.

Mary

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75RR
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Re: Condensers - venting frustration

#7 Post by 75RR » Sun Jun 14, 2020 8:37 pm

This Microscopy Primer is a good introduction: http://www.microscopy-uk.org.uk/index.h ... /intro.htm
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Hobbyst46
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Re: Condensers - venting frustration

#8 Post by Hobbyst46 » Sun Jun 14, 2020 8:56 pm

Maryfox wrote:
Sun Jun 14, 2020 8:16 pm
Working with the condenser aperture diaphragm [url]http://www.microbehunter.com/working-with-the- ... -diaphragm/[/url]
Mary
Just seen the user manual of the CB2000CF. Indeed, it does not have a field aperture. So Kohler illumination is not applicable. The instructions in the underlined link seem valid to your microscope condenser. As mentioned by MicroBob above, it is best to start with the condenser at its uppermost position, especially for the 100X and 40X objectives, and lower it for the 10X and especially for the 4X.
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo

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Maryfox
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Re: Condensers - venting frustration

#9 Post by Maryfox » Mon Jun 15, 2020 1:54 pm

Thanks, everyone. I tend to forget about the UK site, but it should be at the top of my list.
Mary

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Re: Condensers - venting frustration

#10 Post by DonSchaeffer » Mon Jun 15, 2020 2:15 pm

The main take-away I got is that the ability of the microscope to articulate details depends on interference patterns, contrary to what you might think. The diaphragm in the condenser generates interference patterns just like a pinhole camera creates an image. When you close the diaphragm the contrast improves and you can see more details. Of course if you close it too much you cut off the light--the brightness. It's a balance. But the diaphragm is especially important for the higher power objectives.

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Re: Condensers - venting frustration

#11 Post by BramHuntingNematodes » Mon Jun 15, 2020 3:05 pm

Let's say you want to look at something small. You use a magnifying glass. You want to see the object better so you get a flashlight. You want to increase the magnification even more, you get a microscope. Now the lens is too close for you to put your flashlight up close, so, as an expediency you put the flashlight behind the object. Now you have a transmitted light microscope. It gets really dim at high magnifications, so you think, "what if used lenses to make this light like a really tight spotlight on my object?" You want this setup to be reasonably sized so you use two lenses. You call this a condenser, as it collects all the light and condenses it into a brighter, small area. This brightens up the image, but now you have lots of light bouncing all over the place which gets in the way of your observation, so you set up a light blocking device you call a condenser diaphragm to make the spotlight wider or narrower and a rack to move it up and down so you can focus all the light exactly where you want it. This is an Abbe condenser.

You notice that your light is really bright, so bright that you can see the fine details of the outline of the filament of you flashlight bulb. This is pretty annoying and sometimes you get those green after images when you close your eyes. You put a ground glass diffuser over the flashlight, and this kind-of works but the diffuser throws a lot of light around as that is what diffusers do. You put another diaphragm in front of your diffuse flashlight to block out the glare. That's the field diaphragm. Now you notice that the light is dim again that's no good that's why started on this twisty path in the first place! You put another lens in front of the diffuser but behind the field diaphragm to help direct more of the scattered light to your abbe condenser and now, hey, this works well! You notice that with a little fiddling you can have a nice even field of light with or without the diffuser. Neat. This is Kohler illumination.

Then you get up to really high magnifications and notice fuzzy color fringes and distortions and this is where the aplanat and achromat condensers come in.
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Tom Jones
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Re: Condensers - venting frustration

#12 Post by Tom Jones » Mon Jun 15, 2020 4:06 pm

Maryfox,

As you have found out, basic microscopy with low magnifications and relatively low expectations is pretty easy. Once you start up the slope wanting more, it gets a lot more complicated.

I've posted this once before several years ago viewtopic.php?t=3573 but it seems an appropriate time for a revisit.

Take a look at this tutorial: "Understanding the Light Microscope" by Peter Evennett: https://www.youtube.com/watch?v=60_jgZtyR6U

I wish I had seen this years ago. It is a very, very nice demonstration about how the light microscope works. It lasts 1hr, 18min or so, but is well worth your time, particularly as a beginner. He uses a modified microscope, not the dreaded ray-trace drawings normally used to explain how the images are formed. I use this as one of my educational resources when doing microscopy outreach.

You may need to Google a term or two, but it shouldn't be too difficult to understand, and it will probably answer most of your questions.

Tom

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Maryfox
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Re: Condensers - venting frustration

#13 Post by Maryfox » Tue Jun 16, 2020 12:38 pm

Tom Jones -
Thanks very much for the links.
Mary

Hawk_za
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Re: Condensers - venting frustration

#14 Post by Hawk_za » Sat Jul 04, 2020 8:54 pm

Tom Jones wrote:
Mon Jun 15, 2020 4:06 pm
Maryfox,

As you have found out, basic microscopy with low magnifications and relatively low expectations is pretty easy. Once you start up the slope wanting more, it gets a lot more complicated.

I've posted this once before several years ago viewtopic.php?t=3573 but it seems an appropriate time for a revisit.

Take a look at this tutorial: "Understanding the Light Microscope" by Peter Evennett: https://www.youtube.com/watch?v=60_jgZtyR6U

I wish I had seen this years ago. It is a very, very nice demonstration about how the light microscope works. It lasts 1hr, 18min or so, but is well worth your time, particularly as a beginner. He uses a modified microscope, not the dreaded ray-trace drawings normally used to explain how the images are formed. I use this as one of my educational resources when doing microscopy outreach.

You may need to Google a term or two, but it shouldn't be too difficult to understand, and it will probably answer most of your questions.

Tom

Thank you so much for posting this it has helped me understand a hell of allot more than i did before

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