Mitch,
Can you describe how you did the oblique brightfield?
Don't remember which scope I took this with, but it was one of two ways...
One microscope used at that time had a "rotate out" filter holder at the base of the condenser. With this one I made up opaque paper disks that fit into the filter holder. These disks had apertures of various sizes and shapes (Usually off-center round holes or crescent shapes). If needed I moved these new "apertures" around by rotating the filter holder in/out slightly until I got the desired oblique effect.
The other microscope had a phase contrast condenser with rotating turret positions. I would use the normal brightfield position, but rotate the turret slightly (as if I were going to position a phase annuli) so that the aperture moved off center. This provides the oblique lighting. (This is not the same as de-centering the entire condenser itself... it is de-centering the condenser aperture only).
From the pictures you posted it does not appear that you have a filter holder under your condenser. But you could get some black opaque paper and cut some holes and tape it "off-center" to the bottom of the condenser. You would need to experiment with the hole size and position, but oblique brightfield can be very effective.
Look a "Figure 5" on this page:
http://www.olympusmicro.com/primer/tech ... intro.html
Also look under the "Types of Illumination" page on this link:
http://www.mbstevens.com/mscope/index.html#top
(BTW... this last link has a lot of good, easy to understand info in the various sections. It can explain great deal, and inspire you to try various techniques).