Diatoms in epi DIC

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Scarodactyl
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Diatoms in epi DIC

#1 Post by Scarodactyl » Thu Jul 22, 2021 5:58 am

I recently bought a couple slides from Diatom Lab so I'd have a good subject to look at in a future (likely futile) project of diy transmitted DIC. I've been having fun with these, looking at them with my new Leica "Rottermann contrast" base (which is basically a tunable oblique system for low magnifications). I also put the slide under my main scope and was surprised to get what looked like pretty good contrast using epi DIC.
Imagediatoms in epi DIC by Stephen Challener, on Flickr
Taken with one of the cheap Nikon 20x/0.75 plan apos, pushed up to 40x with my mag changer.
I think this would look better if I weren't having some vibration issues with my table--still, I am pretty happy with the look. I had fun with oblique/darkfield but this is definitely more dramatic.

PeteM
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Re: Diatoms in epi DIC

#2 Post by PeteM » Thu Jul 22, 2021 6:16 am

Beautiful images. Thanks for posting them.

Scarodactyl
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Re: Diatoms in epi DIC

#3 Post by Scarodactyl » Thu Jul 22, 2021 6:55 am

Thanks!
If anyone was curious this is how brightfield and rottermann looked on the Leica base.
Image
These were shot with a 20x/0.60 'hr' objective meant for no cover slip mounted on my leica z6. I don't have the right adapter to mount the nikon 20x, but the similarly specced olympus 20x sapo got poorer results with rottermann, though much better with darkfield. I haven't taken any pictures with that combo yet though.

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75RR
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Re: Diatoms in epi DIC

#4 Post by 75RR » Thu Jul 22, 2021 7:20 am

.
Very nice!

Had not come across Rottermann Contrast before this. Works very well.
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

Phill Brown
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Re: Diatoms in epi DIC

#5 Post by Phill Brown » Thu Jul 22, 2021 8:48 am

Thanks for sharing.
Leica "TM" are a bit tight with the details on Rottermann "TM".
Diatom lab slides are tempting, it's the postage that has put me off so far.

Scarodactyl
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Re: Diatoms in epi DIC

#6 Post by Scarodactyl » Thu Jul 22, 2021 9:00 am

It's just a syatem that lets you make obliqie backgrounds with either the top dark, the bottom dark or a band of dark with light around it. It is very similar to nikon's OCC but a bit more tunable.

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Re: Diatoms in epi DIC

#7 Post by MichaelG. » Thu Jul 22, 2021 9:28 am

I think this points us in the right direction:
https://worldwide.espacenet.com/patent/ ... S7394593B2
… features 9a and 9b being particularly relevant.
see text commencing column 10, line 52

MichaelG.
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Re: Diatoms in epi DIC

#8 Post by Phill Brown » Thu Jul 22, 2021 9:51 am

Excellent thanks.
Looks like Osram 8v 20W 64255?
50hrs life expectancy, that's not economical at best.

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Re: Diatoms in epi DIC

#9 Post by hans » Fri Jul 23, 2021 6:22 am

Cool photo, I didn't realize epi DIC could work so well on stuff like this. After all the discussion in Louise's thread these reflections in the larger features look familiar...
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microb
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Re: Diatoms in epi DIC

#10 Post by microb » Fri Jul 23, 2021 10:45 am

What does a Leica z6 with Rottermann look like?

Rorschach
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Re: Diatoms in epi DIC

#11 Post by Rorschach » Fri Jul 23, 2021 4:29 pm

Scarodactyl wrote:
Thu Jul 22, 2021 5:58 am
I recently bought a couple slides from Diatom Lab so I'd have a good subject to look at in a future (likely futile) project of diy transmitted DIC. I've been having fun with these, looking at them with my new Leica "Rottermann contrast" base (which is basically a tunable oblique system for low magnifications). I also put the slide under my main scope and was surprised to get what looked like pretty good contrast using epi DIC.
Imagediatoms in epi DIC by Stephen Challener, on Flickr
Taken with one of the cheap Nikon 20x/0.75 plan apos, pushed up to 40x with my mag changer.
I think this would look better if I weren't having some vibration issues with my table--still, I am pretty happy with the look. I had fun with oblique/darkfield but this is definitely more dramatic.
This is very interesting. Which Leica model number is the base (I mean the long one that usually has eight numbers)? Could it be the same that is/was also sold with Leica higher end stereos?

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Re: Diatoms in epi DIC

#12 Post by Scarodactyl » Fri Jul 23, 2021 5:02 pm

It's specifically the tl4000 rc, a discontinued base once sold with high end stereos. It has an external halogen source which I like. I had to hand make an adapter to mount a 32mm column on it though. I'll take some pictures later along with my further experiments.
Just as a general note this line from Leica do seem to be based on the Diagnostic Instruments TL series bases (the bfdf base in particular is almost an exact copy of the discontinued DI TL6000).

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Re: Diatoms in epi DIC

#13 Post by Scarodactyl » Fri Jul 23, 2021 8:07 pm

microb wrote:
Fri Jul 23, 2021 10:45 am
What does a Leica z6 with Rottermann look like?
Image
Z6 mounted on a Wild M400 adapted to an Olympus szx10 coarse/fine focus mount attached to a 32mm column adapted onto the base. I do love my dumb DIYs.
Phill Brown wrote:
Thu Jul 22, 2021 9:51 am
Excellent thanks.
Looks like Osram 8v 20W 64255?
50hrs life expectancy, that's not economical at best.
This one uses an external 150w halogen source. Halogen bulbs are cheap, easy to source and easy to replace. Not too high on my list of concerns.

Alrighty, here's some more pictures. Note that the following stacks are not very good at all--not only is stacking diatom pictures a specialized process, my Z6 is mounted on an olympus coarse/fine focus mount which was definitely not meant for focus steps this fine.
Here's a shot with oblique using the Olympus 20x sapo attached to my Z6--I stopped the z6 down a little bit to avoid ugly smeariness. The leica base does have condenser optics built in but the max NA you were ever intended to have on one of these is 0.50 so it makes sense that it wouldn't be optimized for a 0.75 na objective.
Image
Here are two shots taken with rottermann contrast, the second one with some oblique mixed in by moving the mirror off-center. Note my adapter doesn't place the lens quiiite over the center of the base so these are all a little decentered, even brightfield. I'll get that adjusted eventually.
Image
Image
Going back to the compound scope, here's the Nikon 20x/0.75 but with a bit more shear for some fun color.
Image
And here's an epi DIC picture taken with my 40x/1.0 water immersion objective:
Image
the DIC isn't quite as good I think since this isn't a Nikon objective but it still works.
Anyway, my takeaway is that epi DIC is clearly not as good as transmitted for diatoms, but it's still a nice tool to have on hand. These results could be a lot better with better controlled vibrations as well. Time to go back to looking at gems and minerals.

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Re: Diatoms in epi DIC

#14 Post by MichaelG. » Fri Jul 23, 2021 9:29 pm

Scarodactyl wrote:
Fri Jul 23, 2021 5:02 pm
It's specifically the tl4000 rc […] I'll take some pictures later along with my further experiments.
If it’s not too much bother; could you please include a photo showing items 9a and 9b
The patent only has them in plan view, and the detail is not evident.

Many thanks
MichaelG.
Too many 'projects'

Rorschach
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Re: Diatoms in epi DIC

#15 Post by Rorschach » Sat Jul 24, 2021 6:40 am

Great images! Seems like a good tool.

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75RR
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Re: Diatoms in epi DIC

#16 Post by 75RR » Sat Jul 24, 2021 1:35 pm

Scarodactyl wrote:
Fri Jul 23, 2021 8:07 pm

Here are two shots taken with rottermann contrast, the second one with some oblique mixed in by moving the mirror off-center. Note my adapter doesn't place the lens quiiite over the center of the base so these are all a little decentered, even brightfield. I'll get that adjusted eventually.
Image
Image
Do like these two shots. Good Rottermann Contrast ad!
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

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Re: Diatoms in epi DIC

#17 Post by Javier » Sat Jul 24, 2021 4:52 pm

Beautiful, thanks for sharing!

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Re: Diatoms in epi DIC

#18 Post by Scarodactyl » Sun Jul 25, 2021 6:01 am

75RR wrote:
Sat Jul 24, 2021 1:35 pm
Do like these two shots. Good Rottermann Contrast ad!
Thanks! Yeah, there is very little practical info about it online--there was one very nice video in the Nikon small world in motion contest, but it looks like it was actually shot in pure oblique to me. I will say the results have been a very pleasant surprise.
There is good news on the rottermann front--it looks like the seller I got mine from has two more for sale. This is the only time I have seen them available.
https://www.ebay.com/itm/R176857-Leica- ... 4068231912

Rorschach
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Re: Diatoms in epi DIC

#19 Post by Rorschach » Sun Jul 25, 2021 9:37 am

Scarodactyl wrote:
Sun Jul 25, 2021 6:01 am
75RR wrote:
Sat Jul 24, 2021 1:35 pm
Do like these two shots. Good Rottermann Contrast ad!
Thanks! Yeah, there is very little practical info about it online--there was one very nice video in the Nikon small world in motion contest, but it looks like it was actually shot in pure oblique to me. I will say the results have been a very pleasant surprise.
There is good news on the rottermann front--it looks like the seller I got mine from has two more for sale. This is the only time I have seen them available.
https://www.ebay.com/itm/R176857-Leica- ... 4068231912
Yeah, although one can find useful information and application examples in the Leica brochures. They have newer versions of these bases available too, and the principle seems to be the same as in these ones that date for 2005-2015. The current ones have added automation in them etc., i.e. not too useful for most users, and the price is obviously very high. I found some of these brochures and can post them here I suppose, if there is interest.

That seller had three of these available on bay yesterday but I snatched one :D Of the remaining two, one seems to be a slightly older version, probably from late 2000's and the other one a bit more recent.

I was actually hunting for a Leica BF/DF base but found these and ditched the original plan!

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