A small alga

[gekko]

I'm not sure what this is (any suggestions will be much appreciated!) The closest I could find (although they do not look to me to be the same) were either the cyanobacteria Chroococcus or the green alga Glaucocystis that itself contains symbiotic cyanobacteria (see, for example, http://www.dr-ralf-wagner.de/index-englisch.htm).
The images were taken using the 100x oil-immersion objective (with the condenser oiled to the slide).

1. Oblique illumination:


2. Bright field:


3. DIC:


4. Cross-polarized light with retarder:

[gekko]

These images were also taken with the 100x oil-immersion objective.

1. Bright field:


2. Oblique illumination (note the improved visibility of the bacteria):


3: DIC (bacteria visibility is even better here):


4: Corss-polarized light:

[75RR]

Have never tried my 100 oel. What with the "mess" and the very short working distance I have shied away.
What is your experience in this. Worth it?
Have heard that dry 60x work quite well.

[gekko]

It depends. Once you try it a few times it becomes easier to do and to clean up afterwords. I find the main problem is the very small field of view. The water layer on the slide should be as thin as possible (sometimes I press on the cover glass to "squeeze out" excess water). I have an oil-immersion 40x next to the 100x on the turret, which makes it easier to find things at 40x and then go back to the 100x since both are oil objectives. But I am not too happy with the results I get, and I keep thinking that with practice I will get better results. However, when I compare images of the same object shown at the same size from the 100x and the 40x dry objectives, the 100x has better resolution (as expected). The above images are as large as possible without them getting too blurry, and I don't know if they are already into "empty magnification" territory (my eyesight is not that good-- I'll leave it up to the viewers to judge and hope to be told if they are!)

[JimT]

Excellent images. I just ordered a dry 60X so when I get it I will post my experience Vs. the 100X oil. JimT

[gekko]

Excellent images. I just ordered a dry 60X so when I get it I will post my experience Vs. the 100X oil. JimT

Thank you. I look forward to learning of your experience.