The following pictures are from my attempts today to try oblique illumination on the specimen using a swan-neck halogen illuminator – light shone upwards at bottom of slide obliquely. Photos below are compared to others using bright field with 10W retro-diode.com illuminator – all with Zeiss Standard microscope.
The sample is a piece of plant leaf cut from house plant in our kitchen.
The oblique illumination gives dark field effects – I picked this technique up from Micscape microscope forum (http://microscopy-uk.org.uk/mag/indexmag.html), although my oblique illuminator has currently a very red light so white balance needs to be corrected.
I have used curves function in GIMP2 to remove parts of curve without data from top and bottom of curve and in the image with lot of blue to enhance some parts curve in-between (but not done that on other images).
The pictures show swirls of cells in circular patterns and veins along the leaf.
Zeiss Standard microscope with external halogen swan-neck illuminator:
x10 objective, bright field:
x10 objective, oblique illumination, with white balance correction:
x40 objective, bright field:
x40 oblique illumination, without white balance correction:
x40 objective, with white balance correction: