Walfisch Bay S. Africa diatomes

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Radazz
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Walfisch Bay S. Africa diatomes

#1 Post by Radazz » Fri Jan 11, 2019 8:02 pm

A couple of shots from an antique slide labeled
Circle Group
Diatomeceae
Walfisch Bay
S. Africa
Styrax

Olympus IX70 10x HMC EOS 7D
Seven image stack
Image

Olympus IX70 10x HMC EOS 7D
Fifteen image stack
Image

Enjoy
Radazz
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75RR
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Re: Walfisch Bay S. Africa diatomes

#2 Post by 75RR » Fri Jan 11, 2019 8:18 pm

That is an interesting slide. Any chance you can get a bit closer to some of the diatoms.
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
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Radazz
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Re: Walfisch Bay S. Africa diatomes

#3 Post by Radazz » Fri Jan 11, 2019 8:25 pm

75RR wrote:That is an interesting slide. Any chance you can get a bit closer to some of the diatoms.
Sure. I was concerned more with the composition.
Which did you have in mind?
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75RR
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Re: Walfisch Bay S. Africa diatomes

#4 Post by 75RR » Fri Jan 11, 2019 8:30 pm

Thanks. The second largest in the first image if you can. Like the star shape in the center
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

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Radazz
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Re: Walfisch Bay S. Africa diatomes

#5 Post by Radazz » Sun Jan 13, 2019 10:12 pm

Here it is, 75
30x HMC (300x)

Not a star after all.
Image

Saw this one while looking for the one you wanted. 4 image stack
Image

Radazz
Last edited by Radazz on Mon Jan 14, 2019 2:31 am, edited 1 time in total.
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75RR
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Re: Walfisch Bay S. Africa diatomes

#6 Post by 75RR » Sun Jan 13, 2019 10:26 pm

Thanks, those are great images. Fantastic detail.
Not a star after all.
Indeed. Have to admit I am surprised though, still, can't argue with the larger image.
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

Hobbyst46
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Re: Walfisch Bay S. Africa diatomes

#7 Post by Hobbyst46 » Sun Jan 13, 2019 10:41 pm

What structure causes this splendid spectrum of colors? it is not common among diatoms, is it?

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Radazz
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Re: Walfisch Bay S. Africa diatomes

#8 Post by Radazz » Mon Jan 14, 2019 2:17 am

I think it may be refraction. I see much more brilliant colors with phase contrast or HMC, but even closing the iris in brightfield will bring out some color.
I also see more color in antique diatom slides than in brand new slides.
It’s possible that the mountant and it’s age affect things as well.

I know nothing,
Radazz
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desertrat
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Re: Walfisch Bay S. Africa diatomes

#9 Post by desertrat » Mon Jan 14, 2019 2:24 am

I was wondering if the rows of tiny holes (punctae?), so close together, might be acting like a diffraction grating, separating the colors like the reflections of light sources off a CD-ROM disk, which can be used as a poor man's diffraction grating?

But the colors disappear under high magnification, and I don't know if that would happen with a diffraction grating.
Rick

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Radazz
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Re: Walfisch Bay S. Africa diatomes

#10 Post by Radazz » Mon Jan 14, 2019 2:29 am

How well the sample is cleaned could matter a great deal.
I ordered one of Klaus’ 8 forms test slides, we’ll see what perfect specimens look like.
Radazz
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