A. Microscopy Operating Procedure: Place the microscope close to the edge of the table. Select a suitable stool so that when looking into the eyepiece, your back is straight and your neck is bent at the nape. 1. Lower the body tube by turning the course focus knob until the 10x or 16mm objective reaches the downward stop. 2. Look through the eyepiece and adjust the mirror to the position which provides the brightest and the most evenly illuminated field of vision which is the circular area seen in the eyepiece. Raise the condenser until its top lens at the same level as the stage. Place the slide on the stage and fasten it using the stage clips. 3. Position the specimen area of the slide over the center of the stage aperture. 4. Looking through the eyepiece, raise the coarse focus knob until the image appears. Focus as sharply as possible. Low power objective has a much greater depth of focus and is generally used for the initial focusing and viewing. 5. Adjust the fine focus knob to sharpen the image in the center of the field of vision. 6. When a feature on the specimen is to be examined at a higher magnification, move the slide so that the feature is centered in the field of vision. The higher the power of the objective, the lesser is the area of the specimen surface included in the field of vision. Shift the higher powered objective into place and adjust with the fine focus knob. 7. The eye should be kept at a certain distance from the eyepiece. Be relaxed when looking into the eyepiece and keep both eyes open. Note: on your worksheet, label the different parts of a compound microscope. Take note also of the characteristics of your microscope and fill up table 1. B. Inversion of the Images: Place under the 10x objective a printed small letter e. The letter should be accommodated in the field of vision. Sketch the letter e as seen by the unaided eye and through the eyepiece. C. Movement of the Specimen on the Stage and its Corresponding Movement in the eyepiece: In referring to direction in the field of vision , use the numerals on the face of a clock. For example, the specimen is at 12, at 6, between 1 and 2, between 9 and 10. Now with the letter e still under the objective fill the data in table 2 under observation. D. Depth of Focus: Depth of focus is the thickness of the layer within the boundaries of which all appear to be sharply in focus. As the objective is moved up and down one specimen is in focus at a time. The thickness of this layer is very nearly inversely proportional to the square of the numerical aperture (N.A.). Hence, an objective with a large N.A. will have a small depth of focus. 1. Secure a prepared slide containing three colored threads from you instructor. 2. Place the slide on the stage under the 10x or 16mm objective. 8 3. Focus upward with the coarse focus knob and note which colored thread comes into focus first, second and third. Write your observation under letter D on your worksheet. 4. Repeat this with the 40x and 4mm objective. Again, make your observation. III.B. Laboratory Tools Draw and identify the gicen laboratory items provided by your laboratory instructor. Below your drawing, give the function of each laboratory apparatus.