Kohler illumination

Setting Up Köhler Illumination
1. Focus on the specimen.
2. Close the field diaphragm to its most closed state so that you can see the edges of the diaphragm (may be blurry) in the field of view.
3. Use the condenser focus knobs to bring the edges of the field diaphragm into the best focus possible.
4. Use the condenser-centering screws to center the image of the closed field diaphragm in the field of view.
5. Open the field diaphragm just enough so that its edges are just beyond the field of view.
6. Adjust the condenser diaphragm to introduce the proper amount of contrast into your sample. The amount of contrast added will depend on the sample, however too much contrast can introduce artifacts into your images.
7. Adjust the light intensity as necessary