How to Use a Microscope

Co-authored by Bess Ruff, MA

Last Updated: January 25, 2023 References Approved

A microscope is a device that magnifies an image, allowing you to see small structures in detail. Although they come in a variety of sizes, microscopes for home and school use generally have similar parts: a base, an eyepiece, a lens and a stage. Learning the basics of using a microscope will protect the equipment and provide you with a valuable research tool.

Part 1

Part 1 of 3:

Setting Up the Microscope

1
Learn the components of the microscope. There are multiple essential pieces of the microscope that you need to be able to identify and use properly. The eyepiece is the portion that you will look into to view your specimen. Simple compound microscopes will only have one eyepiece while more complex microscopes will have a binocular eyepiece.^{[1]
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Research source} Here are the components:
- The stage is a platform where you will place your slides for viewing.
- The arm is the portion that connects the base to the eyepiece.
- The objective is the piece that magnifies the image. There are multiple objectives of varying magnifications.
- There are two focus knobs: coarse and fine focus. The coarse focus knob is usually a large knob on the side of the microscope that moves the objective lens towards or away from the slide. It allows you to find your specimen and roughly focus on it. The fine focus is a smaller knob that is used to focus specifically on the specimen. It allows you to fine tune what you’re looking at under the microscope.^{[2]
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- The light source is on the base of the microscope and points up toward the stage. It provides the light for image viewing.
- The diaphragm is just underneath the stage and allows you to vary the amount of light shining on your image.
2
Place the microscope on a clean, flat surface. Clear your surface of any debris that could potentially harm your microscope. Clean the area with a surface cleaner and lint-free rag, if necessary. Make sure the table is located near an electrical outlet.
- Carry the microscope below the base and on the arm. Never pick it up solely by the arm.^{[3]
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- Place the microscope on the table and plug it in.
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3
Keep your microscope manual nearby. Read it carefully, if you want to see instructions on how to handle your specific model. The manual will also have instructions on maintenance and cleaning if those things are necessary.
- Store your manual with your microscope so you can reference it easily.
- If you have misplaced your manual, try searching for a downloadable version of the manual on the website for the maker of the microscope. If you can’t find one online, contact the company directly and see if you can have another one mailed to you.

Part 2

Part 2 of 3:

Preparing Microscope Slides

1
Wash your hands before you begin. Your hands have oils on them that can easily get onto your slides and specimens. These oils can damage both your specimens and the microscope. If you have access to gloves, it is a good idea to wear these as well.
- Keep your hands and the area you’re working as free of dirt and contaminating particles as possible.
2
Keep a lint-free cloth nearby to use to clean and touch the slides. A lint-free cloth is a special cleaning cloth that does not leave behind fluff after you wipe a surface with it.^{[4]
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Research source} Many slides have a charge applied to one side of them to assist in the mounting procedure. This can make them easily attract dust and other contaminants. A lint-free cloth will limit contamination.
- Never use paper towels with the slides. These leave a lot of lint behind.
- If you are wearing gloves you can touch the slide, but try to only pick up slides by their sides.
3
Use prepared slides to begin with. Prepared slides already have a specimen mounted properly. You can buy these at scientific outlets or several may come with your microscope. Once you are comfortable using the microscope, you can try preparing your own slide.
- To prepare your own slide, obtain a specimen you’d like to look at in more detail. Pond water or pollen are great samples to start with.
- Drop a small drop of the water or place a few spores of the pollen directly onto the slide.
- Place a cover slip at a 45-degree angle to the slide and gently let it fall on top of the slide. The water should hold the coverslip in place.^{[5]
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- To preserve samples for longer, add a bit of clear nail polish around the edges of the slide to secure the coverslip in place.
4
Place the slide on the stage of the microscope. Pick up the slide using only the edges, so that you don't press fingerprints onto your clean slide. Fingerprints and oils from your hand can contaminate the slide. You can also use the lint-free cloth to pick up the slide.
- If the slide is dirty, wipe it gently with the lint-free cloth.
5
Secure the slide in place with the 2 stage clips. There are two clips (metal or plastic) on the stage that function to secure a slide in place, so you can remove your hands and focus the microscope. You should be able to slip the slide underneath the clips easily.
- Avoid forcing the slides underneath the clips. They should raise up slightly to allow the slide in. If you are struggling, try getting the slide under one clip at a time. Raise the clip, slip the slide underneath, and proceed to the second clip.
- Slides are quite fragile and can be broken if this step is not done properly.
6
Turn on your microscope. The switch is usually on the side of the microscope. The center of your slide should have a small circle of light appear on it.
- If you don’t see any light, try adjusting the diaphragm until it is open all the way. The diaphragm should have a lever or disc that spins to alter its diameter and change the amount of light coming through. If the diaphragm is closed, you won’t see any light. Move the lever or spin the disc until you see light coming through again.
- If there is still no light, check the outlet or ask for assistance to change the light bulb in the scope.

Part 3

Part 3 of 3:

Focusing the Microscope

1
Adjust your eyepiece, if you have a binocular set. If there is only one eyepiece, you can skip this step. With a binocular eyepiece, turn the eyepieces to find the correct space between the eyes, or interpupillary distance. You should see a single circle of light when you look through both eyepieces.^{[6]
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- If you see two images when you look through the eyepieces, you need to continue to adjust the distance.
- Move the eyepieces closer together or further apart until you see a single circle of light.
- Remove your glasses, if you wear them. You can use the microscope's settings to focus the object according to your sight.
2
Adjust the diaphragm to its widest opening. The diaphragm allows you to change the amount of light on the slide. To begin focusing on your specimen, you want to shine the maximum amount of light on the slide.^{[7]
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Research source} There should be a lever or spinning disc that allows you to alter the diameter.
- Move the lever or spin the disc until the diaphragm is all the way open.
3
Start focusing on the lowest power objective. You may have two or three different rotating objective lenses that you can switch into place to magnify the object. You should start with the 4x objective and increase until it is focused. Usually, the 4x (sometime 3.5x) objective is the standard for the lowest magnification on a basic microscope.^{[8]
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- The low power objective gives you the widest view, and allows you to slowly bring the object into focus without missing it. It is often called the scanning objective for this reason. Starting at the high power objective may mean that you don't see the object or you don't see the full object.
- The two most common high power objectives are the 10x and 40x.
- The eyepiece has a 10x magnification that is multiplied by the magnification of the objective; therefore, the 4x objective gives you a total magnification of 40x (10 times 4). The 10x objective gives you a magnification of 100x and the 40x objective, a 400x magnification.
4
Move the slide to center it on the stage, if necessary.^{[9]
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Research source} Most slides are much larger than the specimen that is mounted on them. If you can see the specimen, try to position it directly in the middle of the light source. If you can’t see it, move the slide slowly around while looking through the eyepiece.
- Remember, the magnification is mirrored, so you will need to move it the opposite direction on the stage to adjust it properly in your lens.
5
Focus the slide using the adjustment knobs and diaphragm. Start with the coarse adjustment knob (the larger of the two knobs), move to the fine adjustment, and then change the light levels. While looking into the eyepiece, slowly turn the coarse focus knob until you start to see the image come into focus.
- Use the fine adjustment knob to focus the slide further.
- Be aware that as you focus, the stage rises closer to the objective. It is possible to raise the stage enough to touch some of the objective lenses, so take care during the focusing process to avoid this.
- Adjust the diaphragm below the stage. Reducing the light may allow the object to look more rich and less washed out.^{[10]
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6
Magnify the image with a higher objective. Switch to a higher objective only when you cannot focus it further with the low power objective scope. The higher magnification will allow you to see more detail in your specimen. Not all high objectives are used with all slides, since some can focus too closely.
- Use caution when switching between objectives to avoid breaking the slide.
- Use the fine adjustment knob when working with the higher objectives, such as the 10x option. Because the coarse knob moves the objectives closer to the stage, the slide can crack if you’re not paying attention.
- Switch between different objectives and adjust the focus knobs until you are comfortable using the microscope. Try using different slides to increase your practice.
7
Store the microscope in a dust cover. Lenses can easily be damaged by dust and other floating particles. Keeping the lenses and stage clear of dust will prevent damage from occurring. Only clean the lens with approved solution and a lint-free cloth.

Expert Q&A
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Question

How do I view through a microscope with both eyes open?

Bess Ruff, MA
Environmental Scientist
Bess Ruff is a Geography PhD student at Florida State University. She received her MA in Environmental Science and Management from the University of California, Santa Barbara in 2016. She has conducted survey work for marine spatial planning projects in the Caribbean and provided research support as a graduate fellow for the Sustainable Fisheries Group.

Bess Ruff, MA

Environmental Scientist

Expert Answer

Support wikiHow by unlocking this expert answer.

This requires a binocular eyepiece set up on your microscope. Binocular eyepieces have an eyepiece for each of your eyes.
Question

Why do I need a light source?

Joseph_85

Top Answerer

If there's no light source, the image is too dim to be useful.
Question

How do I decide on exactly the right magnification?

Community Answer

Just experiment with the magnification and focus levels. Fiddle with them a bit until you can see clearly.

Warnings

Never touch the microscope lens with your fingers. You will leave oil and fingerprints on this important part of the device. Clean it with a lint free cloth and special spray, if need be.^{[11]
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