| 4. Performing the centering procedure | Basics |

| Raise the condenser to the upper-most position by turning the knob. |
| Stop down the aperture until the field iris diaphragm image enters the field of view by turning the field iris diaphragm ring in the direction indicated by the arrow.
| Bring the field iris diaphragm image into focus by turning the knob.
| Move the field iris diaphragm image to the center of the field of view by turning the centering screws.
| Gradually open the field iris diaphragm until the field iris diaphragm image is just within the field of view.
| Further open the field iris diaphragm so that it is slightly outside the field of view.
|  | The field iris diaphragm must surround the field of view to prevent unwanted stray light from deteriorating the image. |
|  |  | 5