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Starting out in microscopy? Post images and ask questions relating to the microscope and get answers from our more advanced users on the subject.

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Free2Fish
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Joined: Fri Oct 05, 2012 8:47 am
Location: Manitoba, Canada
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Post by Free2Fish »

Hi folks,

I just joined today and did my first examination of pond water in about 45 years today also. I've dusted off an old Kyowa student microscope, built a stand to mount a point and shoot camera and have taken a number of videos and stills with rather poor results. I'm not concerned since I'm in the process of looking for a better microscope so that end of it will be taken care of. Here is a photo of an unidentified creature that I found today. I think it may be a copepod but am just not sure. If someone can help, I'd love to know what it is since it's a kind of a first. :)

Thanks,
HarryImage

rjlittlefield
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Post by rjlittlefield »

Harry, welcome aboard.

Your subject is a cladoceran, I think -- one of the "water fleas". See for example http://sunsite.ualberta.ca/Projects/Aqu ... s/?Page=28.

Wikipedia has articles on these and copepods. http://en.wikipedia.org/wiki/Cladocera and http://en.wikipedia.org/wiki/Copepod.

Your image actually looks pretty good, especially for first attempt. 3D subjects will always have lots of out-of-focus blurred areas in a single shot, and these little crustaceans are devilishly hard to focus stack because of constant motion. I see a bit of color fringing especially near but not exactly at focus. That's typical of most microscope objectives except for high end "apochromats". The image does look a bit grainy -- you might consider setting lower ISO on the camera if you have enough light and/or a subject that will sit still for a longer exposure.

--Rik

Free2Fish
Posts: 31
Joined: Fri Oct 05, 2012 8:47 am
Location: Manitoba, Canada
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Post by Free2Fish »

Thanks for the ID and the comments. I just checked my camera and the ISO was set at "Auto" so I'd imagine it chose the fastest setting (400).

I took another couple of pictures where the color fringing isn't so evident. I assume the color fringing is the addition of the green and violet or purple coloring...correct? The sun was out a bit for these second pictures.

BTW, all the pictures were a bit flat and I added contrast via Photoshop. The microscope only has a mirror and no condenser.

Cheers,
HarryImage
Image

rjlittlefield
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Post by rjlittlefield »

Free2Fish wrote:I took another couple of pictures where the color fringing isn't so evident. I assume the color fringing is the addition of the green and violet or purple coloring...correct?
Exactly. It's often caused by what's called "longitudinal color aberration", where different colors focus in different planes. That typically shows up as greenish cast for dark things on one side of focus but magenta on the other side. You can see some of this with the hairs in your top image. See http://toothwalker.org/optics/chromatic.html for discussion.

Adding contrast in Photoshop is fine. Whatever it takes.

With more opaque subjects like these insect parts, you might also try illumination from the top, using say a flashlight or a desk lamp. If the reflections get too harsh, you can diffuse the illumination with a bathroom tissue or styrofoam to act as a diffuser.

--Rik

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