Franz,
1. How do you make a oblique brightfield?
2. You use an Olympus 1,67 projection eyepiece. I have only a 2,5 Nikon projection-eyepiece. It is possible to use an Olympus 1,67 eyepiece on a Nikon microscope? (I want to reduce the magnification of my microscope. Nikon does not have a 1,67 eyepiece and the Nikon 2,0 eyepiece is very expensive. What can I do?).
1) I use the brightfield position of my "turret" condenser, but then rotate the turret slightly as if moving it to a different position. This moves the aperture off-center. Then I play around with the aperture size and the amount of decentering. Pulling an eyepiece and looking down at the back of the object will show something like these illustrations:
The effect varies greatly and can be extremely nice and effective. I used it extensively before I got DIC, and, in some cases I still prefer it to DIC.
2) The Olympus 1.67 NFK is no longer made and it has gotten gotten very expensive over the past few years (typically $600 and up). But it was "corrective" and would therefore not be a good choice with newer "infinity" microscopes that do not use correction in the eyepieces. What is the diameter of the tube where you now insert the 2.5X Nikon photo-eyepiece? What have you seen as a price for a 2X? Which camera are you using now?