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  • Microscopes 101

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  • Microscopes

Microscopes 101


Step 1: Moving Your Microscope

Carry the microscope with two hands. Keep one hand underneath the microscope and the other on the arm. The biggest reason microscopes break is not because they wear out, but because they are dropped.

Step 2: Microscope Lens Care

Never touch any lens with your fingers. This leaves oil which is hard to clean and particles which may damage the lens. If a lens needs cleaning, use lens tissue, a lens cloth or a lens pen and be gentle. Do not use your shirt or a towel.

Step 3: Microscope Parts

Learn the parts of your beginner microscope. See the manual or a good website.

Step 4: Prepare a Slide

Prepare a slide. If you are using prepared slides, skip this step for now, but come back later. You will need to learn how to prepare a slide.

We will keep things simple for your first prepared slide. Find some newsprint from a magazine or newspaper, the smaller the print the better. Cut out one letter "e". Place the "e" on a clear glass slide and wet the "e" with a single drop of water. Careful, not too much! We just want to moisten our specimen (the letter "e"), not drown it. Next, place a cover slip (small square of plastic) over the letter "e". The cover slip secures the specimen (letter "e") and it also keeps the objective lens clean in case it accidentally touches the slide. Don't drop the cover slip straight down on the slide or you will end up with bubbles trapped under the cover slip. Bubbles appear interesting under a microscope, but you didn't get a microscope to look at bubbles! To keep things bubble free, place one edge of the cover slip on the slide first, then tilt the cover slip down and over.

Congratulations. You have now prepared what is called a wet mount and it is the basic mount used for nearly all types of specimens. Use it later to see pond water organisms and many other interesting things.

Step 5: Insert the Slide

Place the slide on the stage of the microscope, and secure with the stage clips. Beginners make the mistake of ignoring the stage clips. Wrong! At high magnification, when moving the slide, the stage clips keep the slide in place when you take your finger off the slide. Even the tiny bit of stickiness in your finger from oil on your skin will move the slide enough to lose the specimen when you let go of the slide. This is especially true at high power. Use the stage clips.

Step 6: Set Up for Viewing

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. ALWAYS START WITH THE LOW POWER OBJECTIVE! Memorize this. 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.

Step 7: Light Control

Set the light control. 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. Start with plenty of light, 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. In fact, when you start hunting for pond water organisms, you'll find that many of them avoid light. Use only as much light as you need.

Step 8: Focus the Microscope

Focus slowly. It is easy to focus right past the correct focus point if you are going too fast. If your microscope has two controls, use the coarse adjustment for low and medium power and fine tine with the fine focus knob as needed. If you have the "e" or other specimen under the objective properly, it should now be visible. If it is not, gently move the slide around. This may take several tries.

Compare the position of the "e" or other specimen under the microscope with its position on the slide without the microscope. That's right! The microscope turns everything upside down and it reverses everything right to left as well. Memorize this rule. MOVE THE SLIDE IN THE OPPOSITE DIRECTION YOU WANT YOUR SPECIMEN TO GO. When you want the specimen to move to the right, move the slide to the left. When you want the specimen to move up, move the slide down. This seems strange at first, but with practice you won't even notice it.

Step 9: Greater Magnification

Now for more magnification (power). Center the letter "e" or other specimen in the middle of the field of view as closely to the middle as you can. Rotate the objective that has the medium length over the slide and be sure it clicks into place. Refocus, but slowly. You will only be seeing a part of the letter "e" or other specimen, now. Move the slide slowly back and forth if you cannot see anything. If you get lost and lose the letter "e" or other 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. Don't give up.

Step 10: High Power

If you managed medium power and have the specimen focused and in the field of view, you can try high power. Once again, center a part of the "e" or other specimen in the field of view and slowly and carefully rotate the longest tube objective (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! If your microscope has both fine and coarse focus, use only fine focus at high power. Why? The objective is very close to the slide, now. If you use coarse focus, you can , on many microscopes jam the objective down onto the slide and break the slide. Worse, yet, you may soil and even damage the objective.

You will soon discover that using you first microscope at high power is much more difficult than at low power. It takes practice! The good news is that you don't need high power that often. Most of the things you are going to study with a microscope look better at low and medium power, anyway. Even scientists use low and medium powers for much of their work. Use only enough magnification as needed.

Have fun with your new microscope. There's a whole other world waiting for you to see!

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