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SKILLS LAB 3: USING THE MICROSCOPE (BSB-218) You should complete this skills lab before attempting the microscope quiz on ELM! HOMEWORK: Before entering the lab, read about the history of the microscope on page 2 of your text book and be sure that you can identify the parts of the microscope! Parts of the light microscope: Study the following parts of the microscope. To begin this skill you will need to be able to identify parts of the microscope for the TA. 1. Ocular or eyepiece through which you look. Learn to leave both eyes open while working, to avoid eye fatigue. 2. Body tube . 3. Ocular turret which may be rotated through a full circle to allow infinite positions of the ocular. 4. Nosepiece with 3 or 4 different objectives, all of which are parfocal, i.e. the specimen should remain in focus as objectives are changed one to another, and require only minor adjustment of the fine focus at each change. 5. Objectives are the main working parts of any microscope - the compound lens system which produces the initial real specimen image. There are 4 objectives: low (4x), medium (10x), high (40x), and oil immersion (100x). 6. Arm - used to carry the microscope. Figure S3-1: Parts of the Microscope 7. Stage - upon which the slide with its specimen is placed. Adjustment of the stage height is the method of focusing. 8. Spring clip - used to hold the slide firmly in position. Spring clips DO NOT go over the slide, but rather press the slide into place from the sides. 9. Condenser - the lens mounted below the stage, which catches the light rays from their source and focuses them on the specimen. The condenser should not need adjustment, it should remain in its position just below its uppermost level. The condenser control knob is #12.
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10. Condenser front lens knob - used with medium, high power and oil immersion. Twist it towards you to remove this lens and away from you to position it for use. 11. Iris diaphragm lever controls the diameter of the beam of light coming up from below, and must be adjusted for each objective change. This adjustment is essential for clarity of image. Start with the iris diaphragm about 1/3 closed. 12. Control knob for condenser raises or lowers the condenser and is a real hazard for students who mistake it for the fine focus knob. The condenser should remain in a fixed position. See #9. 13. Coarse and fine adjustment knobs combined - initial turning gives fine adjustment - any continued turning switches automatically into coarse adjustment. 14. Light source - the rheostat which controls the intensity of light is on the right side of the housing containing the light bulb. Setting and focusing the microscope: Watch the video that is available in the lab. Practice the following procedure until you are comfortable with setting up and focusing the light
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This note was uploaded on 06/21/2011 for the course BIO 1A03 taught by Professor Kajiura/boreham during the Fall '11 term at McMaster University.

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