10 easy Steps to Koehler Illumination.
1. Turn on the microscope and place a specimen slide on the stage.
2. Set the diopter rings on the eyepieces to “0” if focusing type and then set IPD.
3. Select 10x objectice and focus the specimen with focus controls using dominant eye only.
4. Focus the specimen for your other eye with the respective eyepiece only.
5. Now close down the “field diaphragm” at the base of the microscope.
6. Focus the diaphragm by raising or lowering the condensor height with control knob.
7. Now open the “field diaphragm” towards the outer edge of the field of view.
8. Using the centering screws on the condensor, center the diaphragm evenly.
9. Now open the “field diaphragm” until it just disappears from view.
10. The microscope illumination is now optimised.
Setting the Aperture diaphragm for optimal contrast.
1. Set the microscope illumination as above and turn the light down low.
2. Remove one eyepiece and look down the empty tube from approx 300mm.
3. Observe the circle of light and slowly close the “aperture diaphragm” until you see it.
4. The optimum setting is when the image of the diaphragm takes up one third of the circle but no more than half. If you close it down too far the image will tend to look grainy (too much contrast), conversely if the diaphragm is open too far it will make the image look washed out.
This setting will change for each individual objective lens as will the “field diaphragm” setting. These settings can be adjusted to a good “go between” medium and high magnification objective lenses for normal use, however when taking photographs through the microscope, these settings are critical, especially in low magnification.
For any further information please don’t hesitate to call us any time for assistance.