Phase Contrast Diatoms

[rnabholz]

Slide surfin' with Phase Contrast

AO 10 Phase Contrast 100x for most, 40x (Gyrosigma) Dark Phase Plan Achro, Canon 70D

Surriella PC 363.JPG (104.33 KiB) Viewed 6232 times

Diatoma PC 373.JPG (52.63 KiB) Viewed 6232 times

Diatom PC 378.JPG (107.14 KiB) Viewed 6232 times

Navicula PC 381.JPG (65.3 KiB) Viewed 6232 times

Caloneis PC 386.JPG (92.79 KiB) Viewed 6232 times

[rnabholz]

More

Surriella PC 376.JPG (86.48 KiB) Viewed 6231 times

Gyrosigma PC 0390.JPG (100.73 KiB) Viewed 6231 times

[vasselle]

Très belles séries images
Cordialement seb

[zzffnn]

Very nice, Rod!

Did you use the same 40x and 100x dark phase objective for John B's unstained floral bud photos? If so, I wonder why the backgrounds appear brown there, instead of black in your diatom photos here?

[rnabholz]

Very nice, Rod!

Did you use the same 40x and 100x dark phase objective for John B's unstained floral bud photos? If so, I wonder why the backgrounds appear brown there, instead of black in your diatom photos here?

Thanks zz

Yes the same set up.

I am not sure what the difference is. Perhaps it could be flare or coloration from the plant material itself? The entire field was covered by the section.

While there is some deritus in the diatom field, it is much less densely covered than the wall to wall coverage in the plant sections.

I believe that I made similar adjustments. Will be happy to find out!

[rnabholz]

Très belles séries images
Cordialement seb

Thank you Seb

[KurtM]

I get the same black background through the 100x dark phase lens, although visually it's more of a deep purple color. My AO 10 with bright phase contrast produces a light lavender-ish background color photographically, which is more of a golden brown visually. Always interesting how the camera can see things differently than the eye. Here's a shot through the AO 100x bright phase...





I think your first one is Cymatopleura. Any reason why no. 3 can't be Navicula? Love the areolae detail!

[rnabholz]

I get the same black background through the 100x dark phase lens, although visually it's more of a deep purple color. My AO 10 with bright phase contrast produces a light lavender-ish background color photographically, which is more of a golden brown visually. Always interesting how the camera can see things differently than the eye. Here's a shot through the AO 100x bright phase...

I think your first one is Cymatopleura. Any reason why no. 3 can't be Navicula? Love the areolae detail!

You are absolutely right about the first one - my mistake, it is indeed Cymatopleura.

I do think that 3 is Navicula too, I was being lazy and didn't look it up to confirm, long tiring day. Thanks.

That bright phase certainly makes thing pop! Pretty, although I think I prefer the dark a bit better. That is not to say if some bright phase objectives popped up I wouldn't avail myself of the opportunity.....

Rod

[billben74]

Nice images. Many thanks.

[KurtM]

The AO bright phase objectives are so rare I was convinced they never really existed, and had been added to the earlier catalogs as a practical joke by bored marketing department guys with devilish natures. Aside from the set I got (in a complete stand from our friend Tom), I have only seen one other set come and go. Note: the ones I have are the older style, but still, grab 'em if you see 'em by all means because they're real performers, particularly good for imaging.

[rnabholz]

Nice images. Many thanks.

Thanks Bill

[gekko]

Rod, very interesting diatom shapes, and very beautiful phase contrast images.
Kurt, your phase contrast image is also very beautiful.
I must try that.

[rnabholz]

Rod, very interesting diatom shapes, and very beautiful phase contrast images.
Kurt, your phase contrast image is also very beautiful.
I must try that.

Thanks Gekko

[c-krebs]

Rod,

These are really good.
I'm a little surprised at how nice these small diatoms look with 100X phase.

[rnabholz]

Thank you Charles.

[75RR]

Getting some very nice detail! Especially like 3 and 4
That is quite a difference between your Dark Phase and Bright Phase. Be nice to see the same diatom in both.

[KurtM]

Can't give a same-diatom-in-both just at the moment, but here's as close as I can get. Dark phase contrast first, then bright phase contrast (also known as 'negative phase contrast' and 'positive phase contrast').

[75RR]

Thanks for the demo Kurt
Have to ask, is your Dark Phase representative or is it extra dark? ;)

[KurtM]

All I can say is that mine gives very dark background (we're talking through the 100x, right?) and evidently so does Rod's. So I'd have to say it's an AO thing. The Zeiss, Olympus KHC, and Nikon Labophot provide bright, or positive, phase contrast so can't compare dark, or negative, phase contrast among makes.

[rnabholz]

Getting some very nice detail! Especially like 3 and 4
That is quite a difference between your Dark Phase and Bright Phase. Be nice to see the same diatom in both.

Thanks 75.

[gekko]

I may be wrong as usual, but my thinking is that the darkness of the background has much to do with the camera exposure. For example, if the phase image has very bright highlights, then to prevent them from being clipped (blown), you decrease the exposure, which darkens everything, including the background. Or is that not what is happening?
By the way, the additional images showing dark and bright phase contrast are also excellent and very nice and sharp.

[KurtM]

I may be wrong as usual

Yep, you're correct, as usual. The dark b/g is that way precisely due to the reasons you cite.

[rnabholz]

While it does not speak to the camera exposure point, I came across the passage below while re-reading the AO 10 Series Phase Contrast Reference Manual, and it discusses the brown and blue colorations that I certainly have seen. For what it is worth:

PCNote.JPG (32.17 KiB) Viewed 6066 times