Which part of the microscope is to be adjusted so that the greatest amount of light will pass through in the stage?

A microscope is a high quality instrument and should last 25-30 years if treated properly and with care. Following these simple instructions will not only help you care for your microscope and keep it in good working condition, but will also help you get the most out of your microscope.

1. When moving your microscope, always carry it with both hands (Figure 1, at left). Grasp the arm with one hand and place the other hand under the base for support.
2. Turn the revolving nosepiece so that the lowest power objective lens is "clicked" into position (This is also the shortest objective lens).
3. Your microscope slide should be prepared by placing a coverslip or cover glass over the specimen. This will help protect the objective lenses if they touch the slide.  Place the microscope slide on the stage and fasten it with the stage clips.  You can push down on the back end of the stage clip to open it.
4. 
   Look at the objective lens and the stage from the side (Figure 2, at right) and turn the coarse focus knob so that the objective lens moves downward (or the stage, if it moves, goes upward). Move it as far as it will go without touching the slide!
5. Now, look through the eyepiece and adjust the illuminator (or mirror) and diaphragm (Figure 3,
   
   at left) for the greatest amount of light.
6. Slowly turn the coarse adjustment so that the objective lens goes up (away from the slide). Continue until the image comes into focus. Use the fine adjustment, if available, for fine focusing.  If you have a microscope with a moving stage, then turn the coarse knob so the stage moves downward or away from the objective lens.
7. Move the microscope slide around so that the image is in the center of the field of view and readjust the mirror, illuminator or diaphragm for the clearest image.
8. Now, you should be able to change to the next objective lens with only minimal use of the focusing adjustment. Use the fine adjustment, if available. If you cannot focus on your specimen, repeat steps 4 through 7 with the higher power objective lens in place. Do not allow the objective lens to touch the slide!
9. The proper way to use a monocular microscope is to look through the eyepiece with one eye and keep the other eye open (this helps avoid eye strain). If you have to close one eye when looking into the microscope, it's ok.  Remember, everything is upside down and backwards. When you move the slide to the right, the image goes to the left!
10. Do not touch the glass part of the lenses with your fingers. Use only special lens paper to clean the lenses.
11. When finished, raise the tube (or lower the stage), click the low power lens into position and remove the slide.
12. Always keep your microscope covered when not in use. Dust is the number one enemy!

Remember, microscopes are expensive scientific instruments. Handle them properly and carefully and they will last for many years!