van Egmond Mask Experiments

Here you can discuss different microscopic techniques and illumination methods, such as Brightfield, Darkfield, Phase Contrast, DIC, Oblique illumination, etc.
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rnabholz
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van Egmond Mask Experiments

#1 Post by rnabholz » Sun Mar 13, 2016 8:40 pm

]As some of you know, I have been spending some time recently exploring the capabilities of van Egmond masks.

In those efforts I have been taken by the way that a single mask, moved around in the light path can create a great variety of effects.

To facilitate my ability to experiment with placement, I made a very simple mod to my condenser. i used some cardboard and created an extended shelf that will support a mask that may be offset to a degree that would cause it to fall otherwise.

With the mask in place I can use the eraser end of a pencil to gently move the mask around while watching at the eyepiece to get a pleasing result.

As mentioned, the various results that the mask can produce is really something. I decided to shoot some images to demonstrate.

The subject was a crystal slide, I found an "island" of crystal.

All of the images below were shot making only a change in the position of the mask. Light intensity, focus, condenser setting, etc were all identical for each shot in the series.

All are single frames.

The only change made to the image in post processing was to crop, rescale to 800 pixel width. No levels, colors, or sharpening changes were made.

The differences in the effect is striking and the information delivered in each is a bit different, permitting one to see various features. For those interested in a more artistic approach, there are a great number of creative possibilities. These were made with a gray mask, but other single or dual color masks open more possibilities.
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Last edited by rnabholz on Sun Mar 13, 2016 8:53 pm, edited 2 times in total.

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Re: van Egmond Mask Experiments

#2 Post by rnabholz » Sun Mar 13, 2016 8:46 pm

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Re: van Egmond Mask Experiments

#3 Post by rnabholz » Sun Mar 13, 2016 8:49 pm

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Re: van Egmond Mask Experiments

#4 Post by zzffnn » Sun Mar 13, 2016 9:54 pm

Great work, Rod. Thank you for showing this.

It would be even more educational, if corresponding objective back lens images are shown. But that is a lot to do, and I won't ask for that. Interested members should be able to experiement and figure out this themselves. Finding out that correlation would enable one to consistently produce similar-looking images. Though different subjects, filter height and NA combinations can change thing around a bit.

Yes, offsetting oblique filter slightly can produce very different looking images, ranging all the way from brightfield to DIC-looking to darkfield.

This is also true for gradient universal filter, up to objective NA 0.65/0.66, at or above that NA, darkfield effect does not show up very well.

So you place your filter between condenser top lens and bottom lens? Isn't the factory condenser iris below the bottom lens? It may not matter that much at lower NA. Just not all condensers have a space between top and bottom lens.

I put my UGF/GUF filters under condensers, as none of my condenser has a space like yours. I use Blutak, or a Lego filter holder, to attach/ hold filters. Photos #5-7 of the following thread show my Blutak approach: http://www.photomacrography.net/forum/v ... 1c385e7e54

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Re: van Egmond Mask Experiments

#5 Post by p3aul » Sun Mar 13, 2016 10:29 pm

Rod I am fascinated by the results obtained by the use of simple patches and filters. I got some black cardboard and am experimenting with cutting out different shaped openings in my patches. Just looking at cheek cells and seeing the actual contours of the cells is exciting for me!

I am intrigued by your results with the Van Egmond masks also. Do you buy these or make them? Do you need a special kind of scope or would my Amscope T400b work. I'm thinking I could make some sort of Slide holder out of cardboard that I could attach to my Abbe condenser.

Thanks,
Paul
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Re: van Egmond Mask Experiments

#6 Post by billbillt » Sun Mar 13, 2016 10:46 pm

These are very, very good!
BillT

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Re: van Egmond Mask Experiments

#7 Post by rnabholz » Mon Mar 14, 2016 12:21 am

zzffnn wrote:Great work, Rod. Thank you for showing this.

It would be even more educational, if corresponding objective back lens images are shown. But that is a lot to do, and I won't ask for that. Interested members should be able to experiement and figure out this themselves. Finding out that correlation would enable one to consistently produce similar-looking images. Though different subjects, filter height and NA combinations can change thing around a bit.

Yes, offsetting oblique filter slightly can produce very different looking images, ranging all the way from brightfield to DIC-looking to darkfield.

This is also true for gradient universal filter, up to objective NA 0.65/0.66, at or above that NA, darkfield effect does not show up very well.

So you place your filter between condenser top lens and bottom lens? Isn't the factory condenser iris below the bottom lens? It may not matter that much at lower NA. Just not all condensers have a space between top and bottom lens.

I put my UGF/GUF filters under condensers, as none of my condenser has a space like yours. I use Blutak, or a Lego filter holder, to attach/ hold filters. Photos #5-7 of the following thread show my Blutak approach: http://www.photomacrography.net/forum/v ... 1c385e7e54

Thanks zz

Yes, I found during my pursuit of high NA darkfield that placing the mask on the lower unit of the condenser gave me more consistent results, and find the same thing with the other masks.

That said, anybody with a filter tray or slot, or as you demonstrated, a way to attach a mask should be able to produce good results.

They are so inexpensive to make, and open so many possibilities that I highly recommend them.

Thanks for the interest

Rod
Last edited by rnabholz on Mon Mar 14, 2016 3:26 am, edited 1 time in total.

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Re: van Egmond Mask Experiments

#8 Post by KurtM » Mon Mar 14, 2016 12:30 am

You're really raising the van Egmond effect to an art form, the above images are startlingly exquisite! An alternative name for the masks might be the "not-so-poor man's DIC". :shock:
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Re: van Egmond Mask Experiments

#9 Post by rnabholz » Mon Mar 14, 2016 12:34 am

p3aul wrote:Rod I am fascinated by the results obtained by the use of simple patches and filters. I got some black cardboard and am experimenting with cutting out different shaped openings in my patches. Just looking at cheek cells and seeing the actual contours of the cells is exciting for me!

I am intrigued by your results with the Van Egmond masks also. Do you buy these or make them? Do you need a special kind of scope or would my Amscope T400b work. I'm thinking I could make some sort of Slide holder out of cardboard that I could attach to my Abbe condenser.

Thanks,
Paul
Hi Paul,

I looked up your scope, not sure that I see a filter/mask tray or slot. Don't let that stop you, all you need is a way to suspend a mask below the condenser. As you see above, you can make simple rigs from cardboard, or similar materials that are non destructive and completely reversible easily enough with a little playing around.

As far as my masks, I use Microsoft Publisher to draw them, print them on a laser printer onto overhead transparency film, then stack 3 layers to get the proper opacity or color density. A couple of small drops of super glue between the layers down in the handle area holds it all together.

Hope that answers your questions. Let me know if I can help more, and thanks for the interest.

Rod

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Re: van Egmond Mask Experiments

#10 Post by rnabholz » Mon Mar 14, 2016 12:36 am

billbillt wrote:These are very, very good!
BillT
Thank you Bill

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Re: van Egmond Mask Experiments

#11 Post by rnabholz » Mon Mar 14, 2016 12:41 am

KurtM wrote:You're really raising the van Egmond effect to an art form, the above images are startlingly exquisite! An alternative name for the masks might be the "not-so-poor man's DIC". :shock:
Thanks Kurt. I am having lot of fun exploring them. I hope others jump in and give them a try.

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Re: van Egmond Mask Experiments

#12 Post by zzffnn » Mon Mar 14, 2016 12:43 am

Rod,

I saw an AO darkfield condenser on your "project shelf". That looks like the exact one I have. If you look at it, its daekfield stop is placed at the top lens.

Centering condenser in darkfield is quite critical, once you do that, you will have beautiful images all the way to your oil objective, if you have a funnel stop or iris objective.

Did you get some darkfield funnel stops for your oil objective? If not, Phil may have it for you. With super thin diatoms, you may be able to go up to NA 0.95 without iris objective or funnel stop, but in many cases, you may want to stop down to less than NA 0.8, or even NA 0.65-0.75. Funnel stops do that for you. If not stopping down, you may have annoying halos with thick subjects.

The thing I like about oblique (UGF, van Egmond, ect) is that halos is usually not a problem and internal resolution is usually better. But then outline/contrast is not as great as darkfield.

Edit:

I am sending half of your van Egmond masks to Kurt. He WILL play with them.

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Re: van Egmond Mask Experiments

#13 Post by rnabholz » Mon Mar 14, 2016 1:09 am

zzffnn wrote:Rod,

I saw an AO darkfield condenser on your "project shelf". That looks like the exact one I have. If you look at it, its daekfield stop is placed at the top lens.

Centering condenser in darkfield is quite critical, once you do that, you will have beautiful images all the way to your oil objective, if you have a funnel atop or iris objective.

Did you get some darkfield funnel stops for your oil objective? Phil may have it for you. With super thin diatoms, you may be able to go up to NA 0.95 without iris objective or funnel stop, but in many cases, you may want to stop down to less than NA 0.8. Funnel stops do that for you. If not stopping down, you may have annoying halos with thick subjects.

The thing I like about oblique (UGF, van Egmond, ect) is that halos is usually not a problem. But then contrast is not as great as darkfield.

Edit:

I am sending half of your van Egmond masks to Kurt. He WILL play with them.
Hey zz

That is definitely a project. It was one of those " Oh, what the heck " eBay deals, so cheap that I thought I might be able to put a kit together. The condenser is all I got for my $15.

It doesn't fit the One Ten, but I have a 10 that I am piecing together that it will fit I believe.

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Re: van Egmond Mask Experiments

#14 Post by p3aul » Mon Mar 14, 2016 1:12 am

Rod I can find nothing on the web, other than your videos on Youtube. from your pics here they look like a pattern of variable spaced dots sort of like a magnified picture of a newspaper photo, could you posts some links about them? Where did you first hear of them?

Paul
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Re: van Egmond Mask Experiments

#15 Post by rnabholz » Mon Mar 14, 2016 1:22 am

p3aul wrote:Rod I can find nothing on the web, other than your videos on Youtube. from your pics here they look like a pattern of variable spaced dots sort of like a magnified picture of a newspaper photo, could you posts some links about them? Where did you first hear of them?

Paul
You bet. Here is where I first heard of them:

http://www.microscopy-uk.org.uk/mag/art ... iydic.html

As you can see, it is also called DIY DIC.

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Re: van Egmond Mask Experiments

#16 Post by zzffnn » Mon Mar 14, 2016 1:39 am

Rod,

Mine has that AO4/10/20 dovetail too. Otherwise, I can trade you mine. IIRC AO10's dovetail is wider, while AO110 has narrower centering dovetail. If you have extra 110 dovetail you may adapt it. Or trim it down. But have to put the condenser as close to center as possible.

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Re: van Egmond Mask Experiments

#17 Post by p3aul » Mon Mar 14, 2016 1:53 am

Oh I see! I was calling it DIY DIC and Oblique illumination! I took a closer look at that first picture and I have made that same patch. I use it the most often. Was going to post some pictures when I get good enough at it. I just put mine in the round filter holder but I can't adjust it that way. I'm going to have to rig up some way like you did to adjust it somehow. I can't wait to look at live protists with using that filter!

Paul
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Re: van Egmond Mask Experiments

#18 Post by einman » Mon Mar 14, 2016 2:44 am

These are fascinating! I had acquired a Leitz #56 condenser not too long ago for my Leitz scopes that has a tray for inserting filters. I recently purchased a set of oblique filters and was anxious to try them. These photos only make me want to more more so!

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Re: van Egmond Mask Experiments

#19 Post by rnabholz » Mon Mar 14, 2016 12:56 pm

einman wrote:These are fascinating! I had acquired a Leitz #56 condenser not too long ago for my Leitz scopes that has a tray for inserting filters. I recently purchased a set of oblique filters and was anxious to try them. These photos only make me want to more more so!
Thank you einman. The results can be very interesting. Be sure to post your results, I know people would love to see them.

Rod

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Re: van Egmond Mask Experiments

#20 Post by einman » Mon Mar 14, 2016 2:49 pm

rnabholz wrote:
einman wrote:These are fascinating! I had acquired a Leitz #56 condenser not too long ago for my Leitz scopes that has a tray for inserting filters. I recently purchased a set of oblique filters and was anxious to try them. These photos only make me want to more more so!
Thank you einman. The results can be very interesting. Be sure to post your results, I know people would love to see them.

Rod

I will do that!

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Re: van Egmond Mask Experiments

#21 Post by rnabholz » Mon Mar 14, 2016 5:55 pm

If any of you are interested, below you will find links to PDF files of the drawings that I used to make my masks.

You will see on the gray and blue sets, there are 3 densities of the color, a darkfield mask in two sizes, and an oblique mask.

The color page offers some single color and dusk color masks, and an experimental lined mask.

If you have access to an office store like Staples, or even a local print shop, you can have these files printed on overhead transparency film relatively inexpensively.

Cut them out, glue the layers together with a tiny drop off super glue down in the handle portion and start playing.

Links

http://www.homebuiltastronomy.com/vegray.pdf

http://www.homebuiltastronomy.com/veblue.pdf

http://www.homebuiltastronomy.com/vecolor.pdf

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Re: van Egmond Mask Experiments

#22 Post by 75RR » Mon Mar 14, 2016 7:25 pm

Thanks rnabholz, that is very handy.
I downloaded and measured them - they are 32mm on the nose.

Now all we need is a copy of the booklet "How I did it" by rnabholz
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Re: van Egmond Mask Experiments

#23 Post by rnabholz » Mon Mar 14, 2016 8:49 pm

75RR wrote:Thanks rnabholz, that is very handy.
I downloaded and measured them - they are 32mm on the nose.

Now all we need is a copy of the booklet "How I did it" by rnabholz
Ya know I am known for my high degree of technical precision.... Not

What precisely do you want covered in the upcoming best-selling booklet?

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Re: van Egmond Mask Experiments

#24 Post by 75RR » Mon Mar 14, 2016 8:59 pm

What precisely do you want covered in the upcoming best-selling booklet?
Sorry, it was just a playful reference to the movie Young Frankenstein
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Re: van Egmond Mask Experiments

#25 Post by rnabholz » Mon Mar 14, 2016 9:19 pm

75RR wrote:
What precisely do you want covered in the upcoming best-selling booklet?
Sorry, it was just a playful reference to the movie Young Frankenstein
Ah, of course.

What hump?

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Re: van Egmond Mask Experiments

#26 Post by rnabholz » Mon Mar 14, 2016 9:19 pm

Double post

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Re: van Egmond Mask Experiments

#27 Post by billbillt » Mon Mar 14, 2016 9:36 pm

Thanks for the links, Rod...

BillT

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Re: van Egmond Mask Experiments

#28 Post by 75RR » Mon Mar 14, 2016 10:11 pm

What hump?
:)
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Re: van Egmond Mask Experiments

#29 Post by rnabholz » Mon Mar 14, 2016 11:23 pm

billbillt wrote:Thanks for the links, Rod...

BillT
My pleasure Bill

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Re: van Egmond Mask Experiments

#30 Post by gekko » Mon Mar 14, 2016 11:53 pm

Rod, I only had a very quick look (I'll have to study this post later). Amazing work, very thorough, with beautiful results (as always). This must have taken a lot of work. The link to your post should be saved for reference by anyone wishing to embark on similar work, I think.

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