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SNC2D • Biology – Microscopes The word biology means the study of life. Translated from Greek: • • Types of Microscopes • Compound Microscopes • • Image seen with this type of microscope is • Is the most commonly used. You can even living ones. It has high magnification. However, it has a low resolution • A dissection microscope • • The image that appears is • It is used for dissection to get a better because it has a low magnification. Microscope Parts and Function PART EYEPIECE BODY TUBE ARM BASE STAGE STAGE CLIPS NOSEPIECE OBJECTIVE LENS LIGHT IRIS COARSE FOCUS FINE FOCUS FUNCTION Handling the Microscope • The biggest reason microscopes break is not because they wear out, but because they are dropped. • • This leaves oil which is hard to clean and particles which may damage the lens. If a lens needs cleaning, , a lens cloth or a lens pen and be gentle. Do not use your shirt or a towel. Obtain a slide and place it on the stage of the microscope. Secure the slide with the stage clips. • Rotate the objectives on the nosepiece of the microscope until the shortest objective is over the slide and make sure the objective clicks into place. The shortest objective is LOW power. • Low power lens gives the widest field of view and makes it easier to find the specimen when you look through the microscope. Finding the specimen at high power, without first centering it in the field of view at low power, is nearly impossible. • Open the iris if your microscope has an iris or rotate the diaphragm (circular plate under the stage with different size holes) until one of the large holes is centered under the slide. This is your light control. • , but once you have focused and found your specimen in the field of view, start reducing light until you see the most amount of detail. • The brightest setting is typically not the best for contrast and detail • . It is easy to focus right past the correct focus point if you are going too fast. • Use the fine focus knob as needed. power and fine tune with the • Refocus, but slowly. You will only be seeing a part the specimen. • Move the slide slowly back and forth if you cannot see anything. If you get lost and lose the specimen, go back to low power, center the slide and try again. It may take several tries to find a specimen, but this is normal. • If you managed medium power and have the specimen focused and in the field of view, you can try high power. • Once again, and slowly and carefully (high power) until it clicks into place. It will barely clear the slide, so be careful. • The next rule is very important. DO NOT USE COARSE FOCUS ON HIGH POWER EVER! If your microscope has both fine and coarse focus, • Why? The objective is very close to the slide, now. If you use coarse focus, you can jam the objective down onto the slide and break the slide. Worse, yet, you may soil and even damage the objective. Microscope Calculations o To calculate the total magnification of an image that you are viewing through the microscope take the . o The • • • • seen when looking through the eye piece. To measure the filed of view, you will need a see through ruler or grid. Place the clear plastic ruler with the mm markings on the stage and look through the low power objective. Focus your image. . • Total magnification on low = field of view on other power Total magnification on other power = field of view on low power • Size of object = diameter of field of view (µm) number of times the object fits across the field of view • Magnification of drawing = size of drawing in µm size of object in µm Measure the size of your drawing and convert to µm Divide by the size of the object (last slide) Wet Mount Slide • . If your specimen is too thick, then the coverslip will wobble on top of the sample like a see-saw • directly over the specimen. If you put too much water over the specimen, then the coverslip will float on top of the water. • at a 45 degree angle (approximately), with one edge touching the water drop, and let go. Staining a Slide • • As soon as the stain has covered the area containing the specimen you are finished. The stain does not need to be under the entire coverslip. If the stain does not cover the area needed, get a new piece of paper towel and add more stain until it does. Biological Drawings • Drawings, labels, name and other information must be done . • Use . The drawing should be and kept to the . • The of the drawing is simply the name of the object you are looking at. • . • . Do not add structures because you think they should be there. Do not shade or sketch.