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How To Use A Microscope Properly! 

 

 


First of all, since the microscope is very expensive, lets try to figure out a few ways to AVOID the school having to bill YOU for the cost of replacing one!

 

How to figure out the magnification:   eyepiece x objective lense = magnification

 

 

Eyepiece Magnification

Objective Lense Magnification

Microscope Magnification

Scanning Objective

 

 

 

Low Power

 

 

 

High Power

 

 

 

 

 

Procedure:

1. Make sure all backpacks are out of the aisles before you get a microscope! Always carry the microscope with one hand on the arm and one hand on the base. Carry it close to your body. Always take the microscope with the number you signed up for. You are responsible for this microscope!

2. Remove the cover, plug the microscope in, and place the excess cord on the table! If you let the excess cord dangle over the edge, your knee could get caught on it, and the next sound you hear will be a very expensive crash.

3. Make sure the microscope is OK. If not, tell your teacher! Otherwise you will be made responsible for any damage or missing parts!

4. Always start and end with the Scanning Objective (the smallest objective)!!!

5. Open the diaphragm.

6. Lower the microscope stage to the lowest point. Place the slide on the stage with the specimen directly over the center of the glass circle (or hole) on the stage (directly over the light). Then you have a 9 out of 10 chance of finding the specimen as soon as you look through the eyepiece!

NOTE: If you wear glasses, take them off; if you see only your eyelashes, move closer. Look through the eyepiece with one eye and try to keep the other eye open (this helps avoid eye strain). Remember, everything is upside down and backwards!

7. Make sure you are on the SCANNING OBJECTIVE, lower the objective lens to the lowest point, then focus using first the coarse knob, then the fine focus knob. The specimen will be in focus when the SCANNING OBJECTIVE is close to the lowest point, that’s why you start there and focus by slowly raising the lens. If you can’t get it at all into focus using the coarse knob, then switch to the fine focus knob.

8. Adjust the diaphragm as you look through the eyepiece, and you will see that MORE detail is visible when you allow in LESS light! Too much light will give the specimen a washed-out appearance. TRY IT OUT (also with the higher magnifications)!

9. Once you have found the specimen with the SCANNING OBJECTIVE, center the specimen in your field of view and fasten it with the stage clips. Then, without changing the focus knobs, switch it to LOW POWER. If you don’t center the specimen you will lose it when you switch.

10. Be careful when focusing, use the coarse focus knob as little as possible. If you have difficulty focusing, look at the objective lens and the stage from the side and turn the coarse focus knob so that the objective lens moves downward or the stage, if it moves, goes upward. Move it as far as it will go without touching the slide, then carefully move the lense away from the stage.

11. When you switch to HIGH POWER only use the fine focus knob!!! Do not remove the slide when it is on HIGH POWER. The HIGH POWER objective is very close to the slide. Use of the coarse focus knob will scratch the lens, and crack the slide. More expensive sounds . . .

 

 

Tips On Making Good Drawings:

1. Don’t even think of starting your drawing unless you have a PENCIL! Drawings in PEN are UNACCEPTABLE! This is for two reasons:

(a) You can erase pencil!

(b) You can shade in areas more easily in pencil.

2. Each drawing must be about 1/2 page in size, and must include clear, proper labels! Draw a circle with a pair of compasses (Zirkel). The circle indicates the field of view as seen through the eyepiece. In the upper left hand corner of each circle include the specimen name as written on the slide label or the blackboard. In the upper right hand corner, include the magnification.

3. Labels should start on the outside of the circle. All arrows should end with the point touching the object to be labeled! An unlabeled drawing is nothing more than scratches on a piece of paper!

 

 

How To Make A Wet Mount (Nasspräparat):

1. Gather a thin slice/piece of whatever your specimen is. If your specimen is too thick, then the coverslip will wobble on top of the sample like a see-saw.

2. Place ONE drop of water directly over the specimen. If you put too much water over the specimen, then the coverslip will float on top of the water, making it harder to draw the specimens as they float past the field of view! If too little liquid is used, the organisms may be crushed by the cover glass and evaporation will dry up the specimens quickly.

3. Place the coverslip at a 45 degree angle (approximately), with one edge touching the water drop, and let go. Coverslips are very fragile and break easily, handle with care!

 

 

How To Stain a Slide:

1. Place one drop of Methylene Blue stain (be careful, don’t get stains on your clothes, they don’t wash out!!!) on one edge of the coverslip, and the flat edge of a piece of paper towel on the other edge of the coverslip. The paper towel will draw the water out from under the coverslip, and the cohesion of the water (due to the Hydrogen Bonds) will draw the stain under the coverslip.

2. 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.

3. Be sure to wipe off the excess stain with a paper towel, so you don’t end up staining the objective lenses!

4. You are now ready to place the slide on the microscope stage. Be sure to follow all the instructions on how to use the microscope.

 

 

When you have completed your drawings:

1. Turn the revolving nosepiece so that the SCANNING OBJECTIVE objective lens is "clicked" into position!

2. Remove the specimen from the stage.

3. Be sure to wash and dry both the slide and the coverslip and return them to the correct places!

4. If necessary, clean the objective lenses (only with a special lense paper! And never ever touch the lenses with your fingers!!!) and the stage.

5. Unplug the microscope and wrap the electric cord.

6. Take the microscope by its arm and base and return it to the shelf.

7. Clean your table!

 

NOTE: These procedures will remain the same, regardless of the type of stain, or the addition of a hypertonic/hypotonic solution to your specimen.

REMEMBER: Be careful with the equipment, and be sure to leave the lab in the same condition it was in when you arrived.

HAVE FUN!

 

 

Common problems and solutions

1. Image is too dark!

Adjust the diaphragm, make sure your light is on.

2. There's a spot in my viewing field, even when I move the slide the spot stays in the same place!

Your lens is dirty. Use lens paper, and only lens paper to carefully clean the objective and eyepiece lens. The eyepiece lens can be removed to clean the inside.

3. I can't see anything under high power!

Repeat the scanning and low power procedure, then switch back to high power.

4. Only half of my viewing field is lit, it looks like there's a half-moon in there!

You probably don't have your objective fully clicked into place.

 http://shs.westport.k12.ct.us/mjvl/biology/microscope/microscope.htm

http://www.microscope-microscope.org/basic/how-to-use-a-microscope.htm

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