1.2.4: Using the Compound Microscope

In this portion of your laboratory exercise, you will use the compound microscope to observe some prepared slides. It is important that you follow the instructions below to avoid damaging the microscope and to prevent the breakage of any microscope slides.

1. Secure your microscope from the microscope cabinet using the proper transport techniques described previously
2. Place your microscope on the laboratory bench gently and in a secure position
3. Remove the microscope cover, fold it neatly and place it out of the way
4. Plug the microscope in and position the cord so that it is not in the way and is less likely to be caught and drag the microscope off the laboratory bench
5. Turn the power on
6. Ensure the stage is in its lowest position and that the scanning (4x) objective lens is in position (if not use the revolving nose-piece to rotate the lens into position)
7. Place a prepared microscope slide on the stage of the microscope and secure it with the stage clips.
8. Rotate the coarse adjustment knob to move the stage closer to the objective lens
9. Looking through the ocular lens rotate the coarse adjustment knob away from the objective lens to bring the specimen into focus

10. To view the specimen at a higher magnification, rotate the revolving nose-piece to bring the low power (10x) objective lens into position
11. Looking through the ocular lens use only the Fine Adjustment Knob to bring the specimen into focus; Your microscope objectives should be parfocal, meaning that when you are in focus using one objective lens, it should stay in focus when moving to another objective lens, thus a slight rotation of the fine adjustment knob should bring the sample into focus
    

    Fine focus knob - Used to sharpen the image and can safely be used with any objective lens.

    Credit: Sherry Smith

12. Adjust your light intensity as needed to improve the quality of the image by using the iris diaphragm aperture lever
    

    Aperture diaphragm lever is used to adjust the amount of light moving through the condenser to the specimen. Credit: Sherry Smith

13. Repeat steps 10 and 11 to view the specimen with the high power (40x) objective lens...
14. When you are finished viewing the specimen on high power...
15. Rotate the revolving nose-piece so that the space between the high-power objective lens...
16. When you are finished viewing the specimen using the oil immersion lens...
17. Use the lens cleaner and a lens cleaning cloth/lens paper...
18. Remove the microscope slide from the stage.
19. If the slide is a prepared slide remove the oil if present...
20. Ensure that the stage and the lenses are clean.
21. Power the microscope off and position the cord...
22. Place the microscope cover back on the microscope and transport...

On the following pages, complete the activities to practice using the compound microscope. Record your observations as you progress from a large sample to a bacterial smear, the smallest specimen you will visualize this semester.

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