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Compound Microscopes vs. Stereo Microscopes

Images of Stereo Microscope and Compound Microscope

Stereo microscopes and compound microscopes are two distinct types of light microscopes that have many similarities, but some fundamental differences.

It’s certainly worth being aware of these key differences as they impact factors such as the magnification power, working distance and the depth of field, as well as imparting some other very useful qualities. As a result, each is intended for viewing different types of objects and therefore for different applications.

In brief, stereo microscopes offer a lower magnification, but useful qualities such as 3D visualization and depth perception. Therefore, making them ideal for visualization of larger objects.

Compound microscopes provide a much greater magnification power and so are better suited to inspect the microscopic structures in much smaller specimens.

Stereo Microscopes: Defining Features 

Stereo microscopes, also referred to as dissecting microscopes, provide a relatively low magnification, typically 50x and below.

Stereo microscopes have two optical paths, one which is offset from the other. This is because stereo microscopes use two separate objective lenses and eyepieces. This means that different axes of an object or sample can be analyzed at the same time. This key difference provides it with two very useful features – depth perception and 3D visualization.

Stereo microscopes use a type of illumination referred to as incident light illumination (light is reflected off the surface of the object). This allows the visualization of the surface of the object.

These components provide stereo microscopes with superior depth perception and a great working distance. The depth perception relates to the distance between two points in a specimen that both remain clear and focused when viewed.

For these reasons, stereo microscopes are mainly used for viewing opaque objects including insects, minerals, jewelry, coins, watches, hardware, and many other large specimens.

Compound Microscope Diagram

compound microscope diagram

Compound Microscopes: Defining Features

Compound microscopes are able to provide a much larger magnification, which can range from 40x to 1000x or more. They achieve this by magnifying in two stages, the first that uses the ocular lens and the second which uses interchangeable objective lenses, which are often 4x, 10x, 40x and 60x magnification.

Unlike stereo microscopes, compound microscopes only have a single optical path. This means that the specimen can be viewed through the eyepiece at a greater magnification as the objective lenses can be interchanged.

However, since it does not allow provide two different axes of the same specimen to be viewed at once it lacks the depth perception and 3D visualization of a dissecting microscope.

Compound microscopes also use transmitted light illumination (light is passed through the sample).  This often means that samples have to be dissected into smaller slices to enable the light path to travel through the sample and illuminate more of the microscopic structures.

These attributes make compound microscopes well suited for the observation of smaller samples, often sliced into a section to allow the light to pass through them. This commonly includes biological samples such as bacteria, plant cells, and tissues.

Stereo and Compound Microscopes Have Different Optics

Both stereo microscopes and compound microscopes can be used for a wide variety of biological and hobby based activities. Although many models look similar in design, it’s important to remember that they have some very important differences. As you are now aware, the key differences lie within their optics.

Due to the flexibility of having 3 or 4 objective lenses and often interchangeable ocular lenses, compound microscopes offer superior magnification power and so are ideal for looking at small specimens.

On the other hand, stereo microscopes provide a stereoscopic view of a specimen and are more suitable for analyzing larger objects, where 3D visualization and depth perception are useful.

Binocular vs. Monocular Heads on a Microscope

A monocular head on a microscope is a single eyepiece, and a binocular head on a microscope is two eyepieces. Many people assume that a microscope with a binocular head is a stereo microscope, but this is not the case. While stereo microscopes usually have two eyepieces, a compound microscope can have either one or two eyepieces.

A stereo microscope has 2 objective lenses which provide 2 different optical paths to each eye. These two optical paths are at slightly different angles providing a stereoscopic view – a 3D view – of the sample.

A compound microscope usually has 3 or 4 objective lenses which are interchangeable, but the optical path for each objective lens provides the same angle of view of the sample to each eye. While a magnified image of the sample will be seen in enlarged detail, the image cannot be seen stereoscopically.

Compound and Stereo Microscopes Compared

By now, you are probably well aware of the major differences between compound and stereo microscopes (also called dissecting microscopes). However, in summary, here is a brief overview of the differences:

Compound Microscopes: Key Features

  • Use transmitted light illumination (light is passed through the sample), typically from below the object
  • Have a greater magnification power, which can exceed 1000x
  • Have a single optical path so that each eyepiece has the same angle of view
  • Each ocular lens (eyepiece) can be used with  interchangeable objective lenses

Stereo Microscopes: Key Features 

  • Use incident light illumination (light is reflected off the surface of the object), typically from above the object
  • Have a lower magnification, typically 50x and below
  • Have two different optical paths, allowing stereoscopic (3D visualization) of the specimen and depth perception
  • Use two objective lenses and two ocular lenses so that each eye sees a slightly different view of the sample

Do you Need a Compound or Stereo Microscope? 

Although the general rule is that compound microscopes are used for smaller objects and stereo microscopes are used for viewing larger objects, it really depends on the type of objects you are going to be analyzing on a regular basis. Essentially, you can use either type of microscope to view many types of a specimen.

However, sometimes one microscope is more appropriate. 

Stereo microscopes (dissecting microscopes) illuminate objects from above, which allows the surfaces of many large objects to be viewed in a good amount of detail. They even allow you to view the object stereoscopically (3-dimensional), hence their name.

For those interested in viewing much smaller specimens, and the internal structures of specimens, you will require a compound microscope. These microscopes offer a much greater magnification power and illuminate objects from below. These are great for those individuals wanting to view cells, bacteria, fungi, tissues, organs and other small biological specimens.