3. Adjust the height of the condens

3. Adjust the height of the condenser until the image from the field diaphragm appears clearly in the field of view. For some microscopes there is a risk that you will lift the condenser up so high that it collides with the object holder. Therefore care is needed when doing this. 4. Use the centring screws of the condenser holder to bring the image from the field diaphragm into the centre of the field of view. 5. Open the field diaphragm until it just disappears out of the field of view. If necessary, simply re-centre using the centring screws on the condenser holder. 6. Use the aperture diaphragm of the condenser to find the very best compromise between contrast and resolution for the microscopic image. The scale divisions on the condenser can be used as a guideline. Select in accordance with the objective being used. The view in the tube without the eyepiece should look something like the illustration on the right. The diameter of the aperture diaphragm which is then visible should make up approximately 2/3 of the pupil diameter. If the eyepiece should be removed, for checking, then please make sure that no dirt or dust falls into the tube. 7. It is possible to alter the brightness of the bulb using the dimmer. The brightness is always controlled by the bulb brightness and not by the aperture diaphragm. 8. Possibly there is the need of re-adjusting the focus and x-y axis. 9. Observe the object. If another magnification is selected afterwards, then the Koehler illumination does not have to be reset from scratch, only the aperture diaphragm and field diaphragm need to be adjusted as required. As a result you can always check whether the condenser needs to be re-centred.