Auliscus sp

Images made through a microscope. All subject types.

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Beatsy
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Post by Beatsy »

Lou Jost wrote:A monochrome camera would be useful when using violet light, because it would have four active pixels where a Bayer-matrix sensor would have only two (and the red one might be noisy). Edit: Ah-- but you probably use pixel-shifting, which fixes that ....
No pixel shifting Lou, just straight shots (A7rii - 42 megapixels). But the image scale at this mag/N.A. results in massive oversampling anyway - so just picking out the blue pixels from the Bayer array would work admirably. And just using the full de-bayered image isn't too bad either. An example discussing that here...

http://www.photomacrography.net/forum/v ... 8&start=15

rjlittlefield
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Post by rjlittlefield »

Beatsy wrote:perhaps you'll accept this one as a consolation.
Lovely -- thanks!
santiago wrote:those 4 "mountains" are very high!
They do look that way, but I suspect the height is exaggerated.

Beatsy, do you have any idea what are the physical width and depth of the specimen?

--Rik

Lou Jost
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Post by Lou Jost »

Of course you are right, at such magnifications, diffraction makes those extra pixels useless...

Beatsy
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Post by Beatsy »

rjlittlefield wrote: Beatsy, do you have any idea what are the physical width and depth of the specimen?

--Rik
The field of view is 75 microns wide. This specimen is unusually "pointy" which is what prompted me to select it in the first place. It's pretty much as deep as it is wide (including the girdle band, still attached). The frustule itself accounts for a bit more than half of that when I viewed it from the side - probably about 45 microns from the tip of the peaks to the girdle-edge. I used +/-4 offsets for the stereo stacks.

sushidelic
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Post by sushidelic »

Hi Beatsy,

great image!
Just my 2 cents to the resolution vs. pixel pitch debate...
OK, if you take Abbe, Raleigh etc.. the Sony Sensor eats 45nm per pixel at 100x. Let's take a wavelength of 400nm, so with a NA 1.3 objective and a 1.4 condenser, we can separate 180nm. So the 45nm seem way oversampled. Right.
But... first there's your Bayer Pattern. So the A7 RII is actually 90nm per pixel. OK, still half the size of the achievable resolution.
But then, there's Nyquist-Shannon, which is "exactly" achieved.
Then add the sensor noise etc. - which is why I like to set "my" Nyquist limit at at least 3 times the res to be able to deconvolve later.
What I want to say in short: dare to oversample and sharpen for all the tasty detail!

Did I say that this is a great image by the way? I just love them diatoms.

Best regards,
Michael

Beatsy
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Post by Beatsy »

sushidelic wrote:Hi Beatsy,

great image!
Just my 2 cents to the resolution vs. pixel pitch debate...
OK, if you take Abbe, Raleigh etc.. the Sony Sensor eats 45nm per pixel at 100x. Let's take a wavelength of 400nm, so with a NA 1.3 objective and a 1.4 condenser, we can separate 180nm. So the 45nm seem way oversampled. Right.
But... first there's your Bayer Pattern. So the A7 RII is actually 90nm per pixel. OK, still half the size of the achievable resolution.
But then, there's Nyquist-Shannon, which is "exactly" achieved.
Then add the sensor noise etc. - which is why I like to set "my" Nyquist limit at at least 3 times the res to be able to deconvolve later.
What I want to say in short: dare to oversample and sharpen for all the tasty detail!

Did I say that this is a great image by the way? I just love them diatoms.

Best regards,
Michael
Thanks Michael. Agree entirely with what you say.

But...

My Zeiss ICM405 has an internal 3.2x relay lens to get what's displayed in the 35mm reticle to fit on the sensor. So magnification on sensor is 320x!!

I *am* daring to oversample - and then some :D

sushidelic
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Post by sushidelic »

Whohoo a whoppin' 3.2x intermediate... That really cuts down your field of view though - but the detail is awesome!

I'd say: QED ;).

Smokedaddy
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Post by Smokedaddy »

Steve that is absolutely an amazing image of the Auliscus sculptus (or whatever its name). The detail is freaking awesome.

Smokedaddy
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Post by Smokedaddy »

sushidelic wrote:Hi Beatsy,

great image!
Just my 2 cents to the resolution vs. pixel pitch debate...
OK, if you take Abbe, Raleigh etc.. the Sony Sensor eats 45nm per pixel at 100x. Let's take a wavelength of 400nm, so with a NA 1.3 objective and a 1.4 condenser, we can separate 180nm. So the 45nm seem way oversampled. Right.
But... first there's your Bayer Pattern. So the A7 RII is actually 90nm per pixel. OK, still half the size of the achievable resolution.
But then, there's Nyquist-Shannon, which is "exactly" achieved.
Then add the sensor noise etc. - which is why I like to set "my" Nyquist limit at at least 3 times the res to be able to deconvolve later.
What I want to say in short: dare to oversample and sharpen for all the tasty detail!

Did I say that this is a great image by the way? I just love them diatoms.

Best regards,
Michael
Sure wish I understood all that.

-JW:

Jacek
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Post by Jacek »

Very nice

anne
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Post by anne »

Hi Steve,
I can complete with a comment for the special mountant.
It is a Naphtol-Naphthalinsulfid Resin.
The man who has developed it, is Anton Meller.
Unfortunately he died last year.
He published the formulation in 1985 in the german Mikrokosmos, available here on page 55:
http://www.zobodat.at/pdf/Mikrokosmos_74_0001.pdf

RI will be around 1,8.

A very comitted and courageous friend of me has done some batches. After this procedure he gave it a new name: MFH = mountant from hell.
The procedure to produce, the smell if you produce it, the colour, erverything is like deep from the hell :wink:
We were very excited with the first results, very good contrast and high resolution, but the slides are not stable :cry: :cry:

BR
Anne

Beatsy
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Post by Beatsy »

Thanks for the info Anne and for the mountant sample of course. Very nice to use, just a shame it isn't long-term reliable. But for viewing and photography it's still very useful as it is in terms of contrast.

Shorter stacks too(?)

rjlittlefield
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Post by rjlittlefield »

Beatsy wrote:Shorter stacks too(?)
Yes, that should be true. The apparent depth of a specimen varies inversely in proportion to the refractive index RI of the embedding medium, so at same NA it takes fewer frames to cover the depth.

Understanding the details of this process always makes my head hurt. One way of visualizing it is to trace light rays backward, from the objective back to the subject. The cone of light that is determined by the objective's NA is refracted by the mountant to become a "narrower" cone with a smaller vertex angle. Looking from the side, it's that narrower cone that gives more DOF on the subject. Normally a narrower cone would also imply less resolution. But in this case the wavelength of the light is also shortened while it's in the high RI mountant, and the amount of shortening is just what's needed to compensate for the narrower cone. The result is that using a higher RI mountant lets you image the same physical depth at the same lateral resolution in fewer frames. It's one of the very few ways that you can actually move off the usual curve that trades off DOF versus resolution.

See http://www.photomacrography.net/forum/v ... 025#137025 for a demonstration/discussion of DOF in water versus air.

--Rik

santiago
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Post by santiago »

anne wrote:He published the formulation in 1985 in the german Mikrokosmos, available here on page 55:
http://www.zobodat.at/pdf/Mikrokosmos_74_0001.pdf
Amazing pdf!!! Thank you :)
Santiago
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anne
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Post by anne »

Santiago,
if you choose the Main Page and use as keyword Mikrokosmos you will find near all Mikrokosmos Papers over years. All very intersting and still very actual. Enough for month to read.
BG
Anne

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