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What Magnification Do You Need To See Bacteria?

Last Updated: 15.07.24


If you are looking for some kid-friendly microscopes to see bacteria, you need to learn a few things about how you can truly see these tiny microorganisms through the lenses of such a device. The first question to ask is what kind of magnification you need for such a purpose, and, if you don’t know the answer, you can check it out here. If you also need a borescope inspection camera to explore tight spots, see our knockout post


Is a compound microscope a good idea?

Trying to see bacteria with the help of an average compound microscope may not be such a good idea due to certain factors. For starters, you need to have a magnification that goes up to 1000x and cannot be lower than 400x. Therefore, the microscope you intend to use must be able to handle this level of magnification. You wouldn’t use a kitchen scale inside a lab but opt for the best suited version which is analytical balances so go on and discover more about what to use and when.

Also, the overall optics quality must be superior. An average microscope cannot perform as it should if you were to examine bacteria. Besides excellent magnification, you need the lenses to be able to solve the details that you want to observe through the microscope.

Bacteria are challenging to focus

Your microscope should have a high magnification power, as described earlier, but that may not be enough. The device must also stabilize the picture, as you will notice that the bacterial cells can easily appear out of focus. Furthermore, if you want to make sure that you don’t have to deal with this issue too much, you should make sure that the layer of liquid between the cover and the slide is as thin as possible.


Another thing to know: they are transparent

It may not occur to you if you have never watched bacteria through a microscope and these little critters are transparent. Examining single individuals is close to impossible because they are completely see-through and clear in appearance. As they combine in colonies of bacteria, you will notice a certain colorization which makes it possible for you to examine bacteria properly.

Are there bacteria or something else?

How do you know if what you are looking at are actually bacteria? Speckles of dust and other small debris can contaminate your sample, and you’ll not know what you are observing. Also, as bacteria can clump around other particles, they become more difficult to observe. For all these reasons, you need a proper device, and that can be only a top quality model with high magnification.


Why can’t we observe bacteria with the naked eye?

Bacteria, as you may well know by now, are tiny microorganisms that can be found all around us. They can live in the soil, on any living organisms, and even inside us. Their diameter can be as little as 0.2um, and their length is about 2 to 8um.


A few things about magnification and lenses

We talked earlier about magnification, but we must offer an additional explanation so that you understand how to use a microscope for bacteria a little better. For instance, you must know that there are two sets of lenses. One is the objective lens which is the closest to the slide; it will create an image of the sample that is enlarged and turned upside down.

The second set of lenses represents the eyepiece. The primary role of the eyepiece is to offer extra magnification so that you can examine the bacteria in your sample more thoroughly.

To obtain the magnification of a device, you have to multiply the magnification of the objective lens with that of the eyepiece. So, when you hear that a microscope has a 10x magnification eyepiece, but it comes with three different objectives of the next values: 4x and 10x, the actual magnification the microscope offers is between 40x and 400x, with a 100x level in-between.

What is the microscope resolution?

You don’t need only great magnification, but also good resolution. That means that you must pay attention to the various technological specs of different units. The objective lens is the one that provides the resolution, as the eyepiece will only magnify what the objective delivers. This is a pretty important piece of information, as you must not neglect the power of the objective lens.

Also, no matter how great the eyepiece magnification, it will not be able to make the picture of what you see clearer if the objective lenses it comes along with are of inferior values.


Various magnification levels and what they can identify

Here is a short guide on what your microscope can see, depending on its magnification. You will be able to tell which ones are better for examining bacteria and running various experiments.

40x models are useful for seeing large cells. You won’t be able to study details, and bacteria are out of the question. But, for school projects that only involve some basic examination of various samples, such units can be all right.

At 100x magnification, you will start to see something akin to small dots. These dots are bacteria, but we are still far from being able to say that you can examine bacteria properly. One advantage is that the depth of field remains decent at this magnification and you can see the entire specimen. Focusing is not yet an issue.

At 400x, you will start to examine bacteria as you wish. You will also be capable of noticing cell divisions and even chromosomes. Bacteria are visible, too, and you can observe their shape and other details. However, you must be aware that you’ll have to get handy with the focusing knob as you will not be able to hold a stable image for long.

Finally, 1000x magnification is what you must have for observing bacteria as you should. But, be aware that your unit should have great stabilization features. Losing focus is easy at this level of magnification, and that’s why not any microscope will do. Also, you must use immersion oil to obtain better resolution.

Electron microscopes, without a doubt, are ideal for observing bacteria. However, they are mainly used by professionals, and they are more expensive than their compound counterparts.



Ioana Moldovan

Ioana’s professional experience in the optics field has helped her understand the value of passing her knowledge forward. Her curious personality helps her gather useful information for her readers and her goal is to make technical information fun and accessible to everyone.

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