A small microorganism

[gekko]

I'm not sure what this might be; the best guess I could come up with, and I am almost certainly way-off, is Chlamydomonas but I couldn't see any flagella. All images taken with the 100x oil-immersion objective with the condenser oiled to the slide [DIC, bright field, cross-polarized illumination].

[Edit] I forgot to say that the first image is a focus stack of 15 images taken at 1 µm focus steps and stacked using CombineZP.

[Crater Eddie]

Whatever it is, those are nice images of it.
CE

[mrsonchus]

Excellent detailed images, they have a 3D-quality about them, as well as superb colours.

[gekko]

CE and John, many thanks for your kind words.

[Mintaka]

A very nice picture indeed. The reddish chloroplast makes me want to say Haematococcus. Also, thanks for drawing attention to "CombineZP" ... I'll be sure to check it out.

[75RR]

At 10µm that is very impressive.

[Edit] I forgot to say that the first image is a focus stack of 15 images taken at 1 µm focus steps and stacked using CombineZP.

How are you getting 1µm focus steps?

[Rodney]

Very nice clean images, what type of camera are you using?

Rodney

[gekko]

A very nice picture indeed. The reddish chloroplast makes me want to say Haematococcus. Also, thanks for drawing attention to "CombineZP" ... I'll be sure to check it out.

Thank you!

Haematococcus: you may well be right. The reason I didn't consider Haematococcus was that I thought I was quite familiar with it (I've taken many images, some of which can be seen at viewtopic.php?f=6&t=261&p=1198&hilit=ha ... ccus#p1198 ) and the above images looked rather different to me, but then I don't really know what details to consider in identifying them. Thank you for your suggestion.

Stacking: yes CombineZP is good and free. You may also want to look into PICOLAY, another good, free program. My understanding is that when stacking it is best to take the images in order starting from the part closest to the objective (i.e. start with the objective farthest from the cover glass and focus closer step by step).

[gekko]

At 10µm that is very impressive.

Thank you. I've never been happy with the results I get from my 100x objective, so you're saying that it gave a good image makes me happier .

How are you getting 1µm focus steps?

I relied on the calibration marks on the fine focus knob; I guess I should've said "approximately 1 µm"

Very nice clean images, what type of camera are you using?

Many thanks, Rodney. I use a µ4/3 ("mirrorless") Olympus E-P1 camera body and a 2x projection lens in the phototube.

[75RR]

I relied on the calibration marks on the fine focus knob; I guess I should've said "approximately 1 µm" :)

Got me wondering what the fine focus graduations represented on my Zeiss RA.
Bit fiddly - but basically drew a line (in pencil) across the base/focus block and turned the dial 360˚as it is so marked.
Drew another line with the same bit of plastic and measured the spacing between the two lines.
The fiddly bit entails holding up the plastic (now marked with two parallel lines 1mm apart) to the marks on the focus block while holding a flash light and a magnifying glass.
More than 1/2mm not quite 1mm so calling it 3/4mm
750µm ÷ 360 = 2.08µm ... approximately :)

P.S. I do not focus stack by using the graduations on the focusing dial but do it visually - in small steps looking to "carpet" the sample with small focused areas which hopefully the stacking software will pick up.

[JimT]

First of, beautiful images! Well worth the effort with the OI obj.

Second I agree with Mintaka, looks like images of Haematococcus on the web and is the right size. Surprised you couldn't see the flagella in the DIC image.

Others (including you) have posted images in the past that look like these. I will have to get a bird bath

[Crater Eddie]

In the dormant, or "encysted" stage, haematococcus do not have flagella, or at least I have never seen one at this stage.

[gekko]

P.S. I do not focus stack by using the graduations on the focusing dial but do it visually - in small steps looking to "carpet" the sample with small focused areas which hopefully the stacking software will pick up.

I sometimes do that, but for objects with significant depth, I don't know how that would affect the final appearance.
I indicated above that I was not happy with the results I get with the 100x objective (the 40x seemed to show better resolution), so this afternoon I used Kemp's 8-form test slide to compare them. I was wrong: the 40x resolved the dots on Pleurosigma angulatum (about 525 nm) but not Frustulia rhomboides (about 300 nm) whereas the 100x oil-immersion did resolve the dots on the latter.

First of, beautiful images! Well worth the effort with the OI obj.
Second I agree with Mintaka, looks like images of Haematococcus on the web and is the right size. Surprised you couldn't see the flagella in the DIC image.
Others (including you) have posted images in the past that look like these. I will have to get a bird bath

Thank you very much for the very encouraging comments! I think you and Mintaka are probably correct, but I still don't see the resemblance to the Haematococcus that I've seen in the past or to the images I posted earlier (the link is in my reply to Mintaka above), or to those posted by CE. But then I am a very poor judge of those critters .

In the dormant, or "encysted" stage, haematococcus do not have flagella, or at least I have never seen one at this stage.

You are correct. But the resting stage, as far as I've seen, is always perfectly round in shape. The image above is rather oval.