A compound microscope, also referred to as a biological microscope or a brightfield microscope, is distinct from other types of microscopes for the following reasons:
- It typically uses transmitted light illumination – where light passes straight through the sample. This means that large specimens need to be sliced into smaller components in order for them to be analyzed more effectively.
- Compound microscopes provide a single optical path for viewing the sample. This means that the same image can be viewed through the eyepiece using either the left or right eye.
- Compound microscopes are used to observe objects under a very high magnification which can range from 40x to 1000x or more.
- Compound microscopes are perfect for looking at samples that are far too small to be seen by the naked eye such as the cells of biological matter, their inner structures as well as the non-biological microstructures of metals, rocks and textiles.
How Does a Compound Microscope Work?
The main defining feature of a compound microscope is that it has at least two convex lenses within its design. One lens is called the ocular lens that is within the eyepiece of the microscope whilst the other lens – called the objective lens – is placed much closer to the specimen.
This lens configuration can grant a magnification of up to 2000x, with most models allowing you to switch between three lenses at different magnifications e.g. e.g 4x, 10x, 40x and 60x until you can focus on the desired location of your sample.
Compound microscopes also have a component called the condenser lens and iris diaphragm, which are essential for regulating how light is directed at the specimen.
In addition, compound microscopes utilize transmitted light illumination (light is passed through the sample).
Check out our guide for a more detailed tutorial on the parts of a microscope. There are some variations, but this will give you a good understanding of the major principles behind most light microscopes.
Compound Microscope Diagram
Choosing a Compound Microscope
When buying a compound microscope you will need to consider whether you want a monocular, binocular or trinocular microscope. In simple terms, this just means a microscope with either one, two or three eyepieces.
How do you know how many eyepieces you will need? There are a few deciding factors:
- Magnification – Monocular microscopes work well up to 1000x magnification. However, if you want to achieve greater magnification you will want to opt for a binocular microscope.
- Ease of use – Many people prefer to use a binocular microscope simply because they are more comfortable to use.
- Utility – The majority of monocular microscopes do not feature a mechanical stage which is essential for more complicated investigations, whereas most binocular microscopes do include a mechanical stage.
Microscope Construction Quality
Having a microscope which will last is important because they can be expensive. If you’ve spent a lot of money on this instrument, it is important that it lasts as long as possible and works perfectly.
The durability of a microscope can be affected in numerous ways such as:
- how often the microscope is being used
- whether it’s moved around frequently, and
- the materials that it is made of.
A great way to ensure you are securing a microscope that will last is to buy from a reputable brand with a solid reputation. Much like buying other engineered products, buying from a brand you can trust is always advisable.
This will ensure an ergonomic design that is comfortable, and perhaps most importantly a microscope with amazing optics that will provide a great user experience.
Microscope Optical Quality
There isn’t any point spending your money on a compound microscope if it isn’t as effective as you need it to be. It would be a real waste of money if you bought a microscope that didn’t have the quality you needed to perform a task.
Therefore, make sure you take some time to determine exactly what optics are being offered.
Objective lens – The quality of the lens is fundamental to a microscope, in particular, the quality of the objective lens is paramount.
Second, to this, you will want to consider the quality of the eyepieces. The gold standard for a top-notch objective lens is an achromatic lens – or a color correcting lens. These lenses correct bending light, since different colors have a different refraction, causing the image to curve under the lens.
Eyepieces – For the eyepiece, ensure you opt for Widefield (WF) or Super Wide Field (SWF) eyepieces. This will ensure easy viewing – the wider the lens the better for viewing is the common rule.
It can be somewhat overwhelming to see all the choices available on the market and you will, of course, want to know if you are getting a good value product for your money.
Our top picks below should give you a good overview so that you can make an informed decision on your purchase.
Check out our other articles if you want to learn about the history of the microscope or if you already have your microscope and would like a guide to using it properly.
Compound Microscope Uses
Due to their high powered magnification, compound microscopes are used in a variety of industries including the medical and scientific industries. Here is an overview of just some of their most common applications:
- Biologists – By having such a powerful magnification, medical staff, biomedical science students and science researchers are able to examine specimens or objects at a superior resolution and examine intricate details, which could be missed if a microscope with less magnification was used.
- Forensics – Looking for the faintest of clues to help solve a crime or conclude an investigation often requires the help of a microscope. This includes things like hair, skin and blood analysis.
- Students & Research Scientists – Being able to teach the next generation of medical professionals and allied health professionals often includes the use of microscopy. Students are able to appreciate and gain a deeper understanding behind the theoretical knowledge they’re taught.
Check out this Compound Microscope
Omax Lab Compound Microscope
- Magnification: 40x–2000x
- Light: Adjustable LED
- Viewing Head: Binocular
The Omax brand is lesser known than some of the bigger names out there, but they offer value for money with good optical quality.
Pros:
If you’re on the lookout for a budget model, this OMAX 40X-2000X Binocular Compound Lab Microscope is a good choice.
This package contains a LED compound binocular microscope and includes 100 blank glass slides and cover slips, some prepared slides, and a lens cleaning paper booklet.
The microscope has a magnification power of 40x to 2000x using 4 objective lenses, 4x, 10x, 40x, and 100x oil immersion, as well as two eyepieces, a WF10x and a WF20x for a more in-depth view of your specimens.
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This Omax compound microscope comes equipped with a good quality mechanical stage, which in our view is an essential component of a good quality microscope. Positioning a glass slide by hand can be both time consuming and messy, but with handy controls in the form of knobs, positioning the slide and homing in on a specific part of the slide becomes straightforward.
The LED illumination is also highly desirable for the modern microscope user, unlike older halogen lighting; LED is much brighter and doesn’t discolor the sample. This is even more appropriate for live samples, especially since LED is cool to the touch and doesn’t generate as much heat as halogen bulbs, which can easily dry out live samples and even kill them.
This Omax microscope is ideal for analyzing, for example, semen motility, or looking at live samples and carrying out a cell count. It can be used for analysing blood samples such as a peripheral blood smear, although bear in mind that it is only suitable for brightfield microscopy as its condenser can’t go beyond the 1.25NA Abbe Condenser on the model.
Some other great features include:
- A sliding binocular viewing head enables easy adjustment to suit the distance between your eyes
- Coarse and fine focus knobs providing greater visual clarity of the subject
Cons:
The Omax Lab Compound Microscope does not provide the same quality working experience as the more expensive microscopes, but it is very good value for money.
In Summary:
Overall, this model is user-friendly, easy to setup and so is perfect as a gift for students of any age who have a keen interest in science. The bottom line is that this Omax microscope provides a similar standard to those seen in high schools and colleges, yet you could certainly use it in more clinical environments such as microbiology laboratories and veterinary surgeries.