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GaryB



Joined: 29 Jul 2016
Posts: 521

PostPosted: Tue May 29, 2018 8:30 pm    Post subject: Identifications needed Reply with quote

I have two critters that I can't id. I think one is an egg with something moving inside. It has a face, maybe a rotifer? The second I have no clue. It seems amoeba-like but has a ribbed carapace that's visible as I focus up on it. Coleps appear in both videos for scale.

Anyhow, the first is here. Oblique+Schlieren contrast.
https://youtu.be/1IuWV27SCGs


Second in phase contrast.
https://youtu.be/dSr-a_rXnP8
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eward1897



Joined: 19 Feb 2018
Posts: 11
Location: Minnesota, US

PostPosted: Wed May 30, 2018 3:59 pm    Post subject: Reply with quote

I have been humbled sometimes here in the forum by the real experts, but I think:

1. I agree, a rotifer in an egg. In addition to the eye I sometimes see glimpses of the chewing apparatus (mastax), the cilia of the corona at top and late in the video a 2 toed foot curled up from the bottom. On some frames something looks somewhat leg like on the right side but I think that is the dorsal antenna.

I'll attach a photo of a rotifer face in an egg inside (10 o'clock upper left) of a pregnant mom rotifer (using simple homemade darkfield stop).

2. I think it is Thecamoeba sp. I see one of these occasionally and like yours they tend to be large, active ameobas and have a distinctive pellicle with parallel wrinkles.

Nice captures. You use Schlieren contrast? How do you set that up with a microscope?

Ed



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old AO phase optics on Reichert microstar iv ('crappiest microscope ever produced by the hand of man' )
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GaryB



Joined: 29 Jul 2016
Posts: 521

PostPosted: Wed May 30, 2018 6:43 pm    Post subject: Reply with quote

Thanks, Ed.

That definitely is a Thecamoeba. I looked for Amoeba variants but that never showed up, great find!

The egg does look like a Rotifer and I have plenty of them, I also have numerous worms so I wasn't at all sure.

The Schlieren idea was from this site:

http://www.microscopy.cz/html/2514.html

It's an advanced oblique that has other names as well such as SSEE, or single sided edge enhancement, loosely related to Hoffman modulation. It uses a half stop in the condenser and a modulator stop in the objective backplane that gives slit illumination between the two. I like to try all variants I come across. SSEE gives results that can give DIC a run for it's money, and it's free to the intrepid DIY enthusiast. I'm still working on optimal setup but it gives nice results.

More here about 3/4 down the page.

https://micro.magnet.fsu.edu/primer/techniques/oblique/obliqueintro.html
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zzffnn



Joined: 22 May 2014
Posts: 1682
Location: Texas USA

PostPosted: Wed May 30, 2018 9:16 pm    Post subject: Reply with quote

Very nice work, GaryB!

How did you place and hold Schlieren diaphragm at objective back focal plane and what objective did you use?

I found Schlieren hard to implement for objective >= 40x, since back focal plane is oftentimes not accessible. Even when BFP is accessible, I found it hard to hold the diaphragm in place and hard to remove/change.

And many times Schlieren produces too much shadow effect and eats too much light.........

Did Schlieren produce visually better imaging (than offset oblique) for you, in some cases?
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GaryB



Joined: 29 Jul 2016
Posts: 521

PostPosted: Wed May 30, 2018 9:39 pm    Post subject: Reply with quote

Hi Fan

I used my wild fluotar 40x .75. I took the lens unit out of the housing, cut a small segment of card and it's held in place with a small dob of blutac Cool
It's very easy to get to get to the bfp that way and easily reversible or if a different size modulator is needed. I adjust the size of slit either by moving the condenser stop or move the condenser itself. Either way works. I don't have much issue with light as I'm using a Cree XHP 50 LED.

I did find that harsh and excessive shadowing was doing damage, so I added an extra step which makes everything look better. I added a frosted glass disc to the top of the condenser. I have the Axiostar condenser so it's really easy. It's hard to describe the look exactly but it mixes two different oblique methods, Schlieren and Dodt Gradient Contrast in one and it gives nice smooth results. I'm still messing with it all though to try to get best results.

I'm not entirely sold on one oblique method over another. COL, offset COL, offset light, stops, wedge, dodt, they all have their benefits and I swap between them all depending on mood.
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GaryB



Joined: 29 Jul 2016
Posts: 521

PostPosted: Wed May 30, 2018 11:38 pm    Post subject: Reply with quote

Here's another vid of a worm:

https://youtu.be/2mgQyIVauwQ

Sorry about the poor video quality, it's zoomed in at about 7x on the Galaxy S6 cellphone to show small details, nice shallow depth and clean out of focus. I'm quite happy with the results. Another thing is that there is little image shift as focus moves which is a big problem with standard oblique. It looks much better in real life.
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dolmadis



Joined: 07 Dec 2011
Posts: 501
Location: UK

PostPosted: Wed May 30, 2018 11:48 pm    Post subject: Reply with quote

Hi Gary

Can you share a photo or two showing how you set this up on the condenser and objective please?

Very interested to try this out but need some visuals?

Thanks

BR


John
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marvia911



Joined: 23 Dec 2015
Posts: 15
Location: Kiev, Ukraine

PostPosted: Thu May 31, 2018 3:28 am    Post subject: Reply with quote

GaryB wrote:
Here's another vid of a worm:

https://youtu.be/2mgQyIVauwQ



It looks like an infusoria. Moves, too, like an infusoria.
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GaryB



Joined: 29 Jul 2016
Posts: 521

PostPosted: Thu May 31, 2018 4:17 am    Post subject: Reply with quote

Cool Very Happy

some pics of the setup..

objective in bits


modulator patch in the objective back focal plane (guessing position)


frosted diffuser over the condenser top lens


view of back focal plane down the eyetube


The condenser has a half disc stop. The diffuser smooths the slit illumination so that hard lighting is avoided and the light gradient provided by the diffuser gives wideband shading. Neither full Schlieren or full Dodt but a mixture of both that provides very nice pseudo 3d. The condenser stop position can be moved to make the slot wider or narrower. It's supposed to cover 50% of the view.

Hope this is helpful to someone out there. Any suggestions on how to improve this setup are welcome. I love messing around with this stuff.


Last edited by GaryB on Thu May 31, 2018 4:20 am; edited 1 time in total
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dolmadis



Joined: 07 Dec 2011
Posts: 501
Location: UK

PostPosted: Thu May 31, 2018 4:20 am    Post subject: Reply with quote

Very helpful Gary. Thank you. I'll have a go.

BR


John
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zzffnn



Joined: 22 May 2014
Posts: 1682
Location: Texas USA

PostPosted: Thu May 31, 2018 5:17 am    Post subject: Reply with quote

Very helpful, thank you Gary.

Have you tried a gradient ND filter (or printed grey gradient on transparency), instead of using diffusion + condenser slit?

You can print directly from my gradient template here: http://www.photomacrography.net/forum/viewtopic.php?p=173390&highlight=

Have you tried adding frosted diffuser somewhere under condenser top lens, such as in between lenses (if there is enough space originally), immediately under condenser bottom lens or immediately above condenser slit?

By using diffuser over condenser top lens, you won't be able to utilize full aperture of the condenser (you are essentially lowering condenser slightly). That limits your condenser NA to slightly less than NA 0.9, because of the air gap; you may add immersion to all air gaps, though that added air gap may add a bit of mess?
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GaryB



Joined: 29 Jul 2016
Posts: 521

PostPosted: Thu May 31, 2018 5:44 am    Post subject: Reply with quote

I don't have any transparency film at this time otherwise I'd be going nuts with crazy ideas. I'll have to wait until I can afford it.

I have tried just about every combination of stop/diffuser positioning but unless it's at the point of maximum concentration (condenser top) it just appears as a uniform shade and all definition is gone, killing the effect. One more reason transparency film would be useful.

Having the filter on top of the condenser does reduce NA a little but making sure the frosted side is uppermost and almost touching the slide still fills a .75 objective very well. I normally use the Lomo 40x .65 for Schlieren. I just wanted to see if .75 would work too, and it's easier to show the modulator in the photo.

You will be happy to know that COL still works even with the modulator in place, also standard oblique stops as long as they are covering the same general area as the modulator so they don't interfere. It should work with Phase objectives too as the modulator would be outside the area of the phase ring, so switching between phase, bright and Schlieren should be simple... in theory Laughing

Pretty exciting stuff!
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eward1897



Joined: 19 Feb 2018
Posts: 11
Location: Minnesota, US

PostPosted: Thu May 31, 2018 9:15 am    Post subject: Reply with quote

Gary:

1. Regarding the "worm". I think it is a Spirostomum, a sometimes giant heterotrich ciliate (related to Stentor and others). First time I saw them it was with a magnifying glass and I thought they were worms. Some get 4 mm long. Here is a family tree:



Here's a Spirostomum alongside a Paramecium with extra colorful COL (old AO phase objective with incorrect phase annulus and a cheap eyepiece camera creating beautiful color distortions, in my opinion):



2. I'm very impressed by your home brew optical modifications. Thanks for showing us the details. I wouldn't be brave enough to pull a nice fluorite objective apart. Your results are great. Photographers sometimes use 6 or 12 inch diameter curved mirrors that would look more at home in a telescope than a microscope to produce schlieren optics. Maybe you or someone else in this forum could produce an ultimate schlieren telescope-microscope monster hybrid!



It's interesting how well variations of oblique hold up to more expensive and sophisticated contrast techniques. Your video of Spirostomum "worms" has the optical sectioning quality of DIC.

Thanks again for sharing.

Ed
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