Microscope NotesThe compound microscope is a useful tool for magnifying objects up to as much as 1000 times their normal size. Using the microscope takes lots of practice. Follow the procedures below both to get the best results and to avoid damaging the equipment. Show
Field of ViewThe field of view is largest on the lowest power objective. When you switch to a higher power, the field of view closes in towards the center. You will see more of an object on low power. Therefore, it is best to find an object on low power, center it, and then switch to the next higher power and repeat. Depth of FocusThe depth of focus is greatest on the lowest power objective. Each time you switch to a higher power, the depth of focus is reduced. Therefore a smaller part of the specimen is in focus at higher power. Again, this makes it easier to find an object on low power, and then switch to higher power after it is in focus. A common exercise to demonstrate depth of focus involves laying three different colored threads one on top of the other. As the observer focuses down, first the top thread comes into focus, then the middle one, and finally the bottom one. On higer power objectives one may go out of focus as another comes into focus. Microscope TroubleshootingProblem #1: The image is upside down and/or backwards.
Problem #2: Everything is dark.
Problem #3: I can't find anything on low power!
Problem #4: When I moved to a higher power, everything disappeared!
Problem #5: The image is blurry on all powers.
Problem #6: The image is blurry only on a particular power.
Microscope DrawingsWhen drawing what you see under the microscope, follow the format shown below. It is important to include a figure label and a subject title above the image. The species name (and common name if there is one) and the magnification at which you were viewing the object should be written below the image. All relevant parts of the drawing should be labelled on the right side of the image using straight lines. Lines should not cross. Drawings should be done in pencil, while labels should be in pen or typed. Remember that total magnification is determined by multiplying the ocular x objective. Viewing Prepared Slides*** Don't hoard slides! You can only view one at a time, so that's all you should be holding. Return it before getting another, and if you break it, tell your instructor so that it can be properly cleaned up and replaced! ***
Making a Wet Mount (Live Prep) Slide
Further InvestigationDigital microscope for Macintosh or Windows Investigating pondwater organisms Powers of 10 (1977 version) Make your own microscope Why must you center and focus the object in the field of view under low power?The field of view is largest on the lowest power objective. When you switch to a higher power, the field of view closes in towards the center. You will see more of an object on low power. Therefore, it is best to find an object on low power, center it, and then switch to the next higher power and repeat.
Why must the specimen be centered before switching?It's important to center a specimen prior to increasing microscope magnification because, the lenses focus on the center of a subject. If the subject in question isn't centered, when magnification occurs the lenses will magnify whatever is in the center of the optical frame.
What is the position of the specimen as seen under low power objective?The power for the low objective is 10X. Place one of the prepared slides onto the stage of your microscope. Make sure that the specimen is centered over the stage aperture. The light source should be adjusted to medium intensity, the condenser about three-fourths of the way up and the iris should be almost closed.
Where should a specimen be positioned under a microscope under low power to view it correctly?Make sure the specimen is positioned in the center, right under the lowest objective lens. Step 5: Look into the eyepiece and slowly rotate the coarse adjustment knob to bring your specimen to focus. See to it that the slide does not touch the lens.
|