Microscope Parts Explained

Microscope Parts Explained

Microscopes are optical instruments that have been around since the 16th century. These helpful tools allow us to view small objects close up, such as cells and insects. 

You can find microscopes in many school classrooms and science labs. However, microscopes are also great tools to have at home. 

If you want to get into microscopy as a hobby or even a career, it is a good idea to become familiar with all of the microscope parts first. 

While there are many different kinds of microscopes, the most common type you will encounter is the compound microscope, which we will be talking about today.

Knowing the different parts of a compound microscope will help you understand how the instrument works.

It will also help you get over the learning curve faster. 

This guide will explain all of the different microscope parts, including the objective lenses, eyepiece tube, and so on. 

By the end of this article, you will be an expert on microscope parts and will not be overwhelmed trying to figure out how to use one. 

If you are ready to learn more about this topic, keep on reading. 

The Structural Components

The Structural Components

This section will review all of the microscope’s structural components, including the head, base, and arm. 

The main job of these parts is to support the instrument, so they will typically be the heaviest components of the microscope compared to the optical components.

These parts will also house other parts of the microscope, such as lenses and knobs.

  • Head/Body: One of the main microscope parts is the head, or otherwise known as the body. This part refers to the top half of the microscope and holds most of the optical components of the instrument. Most microscope heads will either be a circular shape or square shape. 
  • Base: The base is an important component of the microscope since it supports the entire instrument. Typically, the base will house the microscopes illuminator, which is the piece that lights the specimen from underneath. Since the base is one of the strongest parts of the tool, people will typically carry the microscope while holding the base and arm. 
  • Arm: The arm is the piece that connects to the base of the microscope. It also supports the head of the instrument. The proper way to carry the microscope is to hold it by the arm, which is why this piece is so important. On higher-quality microscopes, the arm will have multiple joints, allowing the head of the microscope to move more easily. This feature will make it a bit easier and more comfortable to view the specimen.

The Optical Components

Now that we have covered all of the structural components, it’s time to look at the optical components of the microscope.

These components include all of the parts that help produce the final image you see through the eyepiece of the microscope. 

Eyepiece Lens

Eyepiece Lens

The eyepiece lens, also called the ocular lens, is the lens at the very top of the microscope. It is the lens that you look through while looking through the eyepiece.

Eyepiece lenses will normally have a magnification level of anything from 5x to 30x, but the standard is 10x.

The power of the eyepiece lens will determine the final magnification power of your microscope. This lens will work with the objective lens, which we will explain below, to create a final power. 

Eyepiece Tube

The eyepiece tube is one of the most important microscope parts. This component is what holds the eyepiece in place. The eyepiece sits above the objective lens. 

There will also be a diopter adjustment ring on the eyepiece tube and an interpupillary adjustment on binocular microscopes.

The interpupillary adjustment piece will allow you to adjust the distance between the two eyepieces. 

However, you will not find these extra components on the eyepiece tube if you have a monocular microscope. 


The nosepiece of the microscope (also called a revolving turret) houses the objective lenses.

There are typically multiple lenses that you can flip through, depending on what magnification level you want.

A standard microscope will normally have the following objective lenses you can choose from: 4x, 10x, 40x, and 100x.

Objective Lens

Microscopes usually have three or four objective lenses. These components are the main lenses that magnify the specimen you are studying.

Each lens has its own power. Some will be facing forward, while others are facing backward.

You will normally find objective lenses with magnification powers of 40x to 100x. Shorter objective lenses will have lower magnification powers, while longer lenses will have higher powers. 

The objective lenses interact with the eyepiece lens to create the final magnification level.

For instance, if your microscope has an eyepiece lens with a power of 10x and an objective lens of 4x, the total magnification level is 40x.

To come up with this number, simply multiply the power of the objective lens you are using with the eyepiece lens. 

Condenser Lens

The main job of the condenser lens is to collect and focus light coming from the illuminator onto the specimen in study.

Without these lenses, you would not be able to see small details of the specimen.

You can typically find this lens next to the microscope diaphragm under the stage. The condenser lens is what helps produce clear images with a high magnification level.

Higher magnification condenser lenses produce sharper images.

Adjustment Knobs

You will find two kinds of adjustment knobs on a microscope; a fine adjustment knob and a coarse adjustment knob. You can use these microscope parts to adjust the focus of the lenses. 


This is one of the most important microscope parts since it holds the specimen in place. The stage is where you put the specimen slide.

There are also clips on the stage that will hold the specimen slides in place. 

While some stages you have to maneuver manually, many modern microscopes come with mechanical stages.

Mechanical stages are easier to move since you can simply move the specimen slides using knobs. 

Rack Stop

The main job of the rack stop is to control how far the stage moves. This, in turn, will prevent the stage from getting too close to the objective lens.

The rack stop will then prevent the objective lens from damaging the specimen slides. 

Without the rack stop, the specimen slide could move too far, hit the objective lens, and possibly damage the slide. 



The illuminator is at the base of the microscope. This component is the main light source that lights the specimen from below.

Standard microscopes will use halogen, low voltage light bulbs. You will find 100v bulbs on many microscopes. 


The aperture refers to the hole in the microscope stage. This hole is where light from the illuminator travels through to light up the specimen.

The aperture of a microscope can vary in size. The hole can be anywhere between 5 and 12 millimeters. 


The diaphragm, also known as the iris, controls the amount of light that reaches the specimen on the stage. You can find this component right under the microscope stage.

The main job of the diaphragm is to control the size of the light beam that hits the specimen. It also controls the intensity of light. Hence, this component is adjustable.

On higher-quality microscopes, you will also find an Abbe condenser attached to the diaphragm.

Abbe Condensor

Not every microscope will have an abbe condenser. You will only find this part on high-quality, more expensive instruments. 

Abbe condensers allow for the condenser to move and be adjustable. Furthermore, this component allows for a higher magnification power of over 400x.

Many high-quality microscopes will have high numerical apertures. 

Condensor Focus Knob

The condenser focus knob, another important microscope part, allows you to move the condenser either up or down.

Doing so will control how the light lands on the specimen on the stage, which will help adjust the focus of the light. 


We hope that this guide has helped you learn more about all of the different microscope parts.

At first glance, microscopes can be a bit confusing. However, once you get the hang of the different parts and how they work, it will not be hard to start using the instrument.

There are two basic categories of microscope parts: the structural components and the optical components. 

The structural components refer to the pieces that support the machine, such as the head, base, and arm.

These parts are normally heavier than other components of the instrument and house additional parts. Next are the optical components of the microscope.

The optical components refer to all the different parts that help produce the final image, such as the lenses, tubes, adjustment knobs, illuminator, stage, and diaphragm.

Mostly all compound microscopes have the same parts. However, higher-quality models will have some additional parts, such as an Abbe condenser with higher numerical apertures.

Furthermore, some parts will be slightly different on alternative microscope models, such as the objective lenses and eyepiece tube.

For instance, you will find a variety of objective lens powers on each instrument.