If you’re new to microscopy, this list is an excellent place to start before you hunt for a microscope. Below we at MicroscopeGenius.com have compiled a list of the 15 questions we are most commonly asked when one who is new to microscopes begins taking an interest and shopping for one.
Whether microscope newbie, novice, hobbyist, enthusiast, or professional, be sure to give this a read before you start looking for a new microscope (or, if any new microscope users or interested parties ask you these, send them here to save yourself some time explaining!)
15 Most Common Microscope Questions for Newbies
1. What magnification does my microscope need be able to see cells?
Typically, not only will you need a compound microscope (a microscope with an illuminator at the base of the microscope that shines up through the slide, into the lens, and creates an image in the eyepiece), but you will need one that will operate to a minimum magnification of 400x.
Most microscopes come with 10x or 16x eyepieces, so you’ll want to be sure it has at least a 40x objective on it if your goal is to view bacteria. (If unsure how to calculate total magnification, keep reading below!)
Here is an example of a microscope starter kit ideal for viewing cells/bacteria: Levenhuk 50L NG Starter Package
2. What magnification does my microscope need to see bacteria?
Bacteria are also cells (typically single cell organisms), so about 400x (10x eyepiece and 40x objective is the most common combination you’ll see for a compound microscope meant to view bacterial cells).
The higher you go, the more detail you will see (up to 1000x total magnification). Beyond 1000x, you’ll enlarge the image, but you won’t add more detail (more magnification, no additional resolution).
Here is an example of a microscope starter kit ideal for viewing cells/bacteria: Levenhuk 50L NG Starter Package
3. What are the different magnifications on a microscope? How do I calculate total magnification?
The total magnification of your microscope is the product (multiplication) of all magnifying elements’ magnification values. So, if you have a compound microscope with 10x eyepieces, and have 4x, 10x, and 40x objectives, then your total magnification options are 40x, 100x, and 400x.
If you are using a stereo microscope, the formula remains, however, if you have any additional Barlow lenses (ones that attach to the objective to change the total magnification higher or lower), then you have to consider those as well.
If using a USB camera for microscopes, keep in mind, these camera sensors typically have some kind of natural magnification, so you need to replace the eyepiece magnification value with the camera’s natural magnification value. Just like stereo microscopes can have Barlow lenses, cameras typically have reduction lenses that cut magnification down (for greater field of view or similar focal distances with eyepieces), so factor that in too. Do not multiply the eyepiece and camera magnification values together, as when you are using a camera, the eyepiece is not in the same path of light as the camera.
4. What type of microscope is most used in science classes?
A compound microscope is the most common type of microscope used in a science class. These have illuminators that shine up from the bottom of the microscope, through a focusing lens called a condenser, through the sample (mounted on a translucent slide), into the objective lens, and creates an imagine in the eyepiece up top.
Compound microscopes are used for translucent, biological samples, and viewing a very high magnification values (allowing you to see things smaller than the naked eye).
Here is an example of a compound microscope that is actually used in many school labs: AmScope 40x-2000x M620B LED Monocular Compound Microscope
5. What is the difference between a stereo microscope and a compound microscope?
A compound microscope has a single path of light that travels in the manner outlined above, which is split before the eyepieces into the number of ocular tubes the microscope has. This means that samples must be translucent enough to pass light through, and that each eyepiece contains the exact same image as the other.
A stereomicroscope, or stereoscopic microscope, is one that commonly has two objective lenses for each magnification setting, which are focused slightly offset from each other. Each lens captures the image individually, meaning that each objective has its own path of light per eyepiece. This is why stereomicroscopes are almost never seen as monocular microscopes–two paths of light are required to create a “3D” (or, stereoscopic) image, allowing the user to see the surface of a sample in great detail.
Samples are typically large enough to handle by hand, and are opaque, as the light travels from above and reflects off the surface to create an image.
6. Should I get a monocular microscope, a binocular microscope, or a trinocular microscope?
Let’s start be defining what each is. “Ocular” refers to the eye, and thus, the tube in which an eyepiece or camera goes into to allow a user to view into the microscope. The prefixes determine the number of ocular tubes on a microscope–“mono-” meaning one, “bi-” meaning two, and “tri-” meaning three.
If the microscope is primarily to be used by children from ages K-12, we would typically say go with a monocular microscope. Many binocular microscopes are a bit too large for younger children to use. Even though the interpupillary distance can be adjusted, often times it cannot be adjusted small enough to fit their smaller widths between their eyes. Often times, you can save money by purchasing a monocular microscope over a binocular microscope as well, so there’s that to consider as well.
We will, however, qualify this, by stating that although a binocular microscope may not fit smaller children, because the image is exactly the same in each eyepiece, they can easily use a single eyepiece on a binocular microscope until they fit the microscope as they grow older. So at the same time, if you don’t mind spending a little more, you can add to “future proofing” your purchase by getting a binocular microscope. Often times, binocular microscopes are meant for undergraduate or medical/professional use, so you can expect higher quality and better options available post purchase with a binocular microscope as well. Binocular microscopes are comfortable for adult use, as the two eyepieces help with eye strain.
A trinocular microscope only makes sense if you have a need that requires it. If you plan to use a USB camera or DSLR camera adapter, a trinocular port is a must. Or, if you need to introduce a laser or beam splitter of some kind (however, if you’re needing to do that, you probably know most of what we have written here already 🙂 ).
We recommend getting one with a simul-focal functionality to adjust the length of the trinocular port to compensate for differences in magnfication between the camera and the eyepieces if you intend to view with the eyepieces, then take a picture with the camera. The easiest way to use a trinocular microscope, however, is by simply viewing the live stream that your camera is displaying on your computer, and adjusting using the screen. Refocusing between a camera and the eyepieces is a huge hassle.
7. What are zooming microscopes and fixed power microscopes?
A zooming microscope is one that has a knob that a user can turn to adjust the magnification value in a continuous range. These are most commonly found on medium to high quality stereo microscopes, and allow a great deal of flexibility in the use of the stereomicroscope. An example of a cost effective but high quality zooming stereomicroscope is this one here: AmScope 3,5x-90x SM-2BZ Zooming Stereo Microscope
A fixed power microscope is one that has several objectives that can be cycled through, but no continuous range or knob to adjust the magnification. Lower model stereomicroscopes, such as ones for children or home use, are commonly fixed power, as are almost all compound microscopes. An example of a cost effective but quality fixed power stereomicroscope is this one here: Levenhuk 3ST 20x-40x Stereo Microscope
8. How do I take pictures through a microscope?
You will need to replace an eyepiece with a USB microscope camera or a DSLR equipped with the appropriate adapter for the camera and inner diameter of the microscope’s ocular tube. If using a USB camera, it has to either fit into the ocular tube or trinocular tube (check inner diameter of the tube where your eyepiece fits and compare that to the outer diameter of the USB camera or adapter that it comes with). From there, install the software to your compatible computer system, run the software, and capture images on your computer. Here’s a perfect example of a USB microscope camera that we use frequently, and fits 23mm, 30mm, and 30.5mm ocular tube sizes (fairly universal, but check first before buying!): AmScope MU300 USB2.0 Microscope Camera
For DSLR users, please consult with your microscope supplier to determine if a DSLR adapter is available for your microscope and camera (it has to fit both), or ask us and we will try our best to determine that answer for you. Canon and Nikon cameras are most commonly supported by the brands we typically focus on. Install the adapter by replacing the lens on your DSLR, attach to the microscope, and capture images through your viewfinder as normal.
9. What is the field of view of a microscope?
The field of view in a microscope is how large the area you’re seeing within the eyepiece is. The lower the magnification, the smaller the image you are seeing in the microscope, and thus, the larger the area you are seeing is, which in turn, means the larger your field of view is.
When you increase magnification, the image you are seeing in the microscope gets bigger, but the hole (the eyepiece) you are looking through remains the same, meaning your have a smaller field of view at higher magnification values.
10. What is the depth of field of a microscope?
The depth of field of a microscope is how deep the focus area is for the given magnification values. This can be a little confusing, but think of it as the field of view, but in the Z dimension (depth) instead of the X-Y (horizontal/vertical) direction.
When you focus a microscope at a given magnification setting, there’s a position where the lens is at the right distance from the sample to achieve a focused image. But, if you notice, when you adjust a little more in either direction from that point, it’s still in focus, but other elements at different depths come into focus, right? How large that area is above and below the point of focus is the depth of field.
If you’re looking at a tall sample but want to see not only the surface but the next surface below it (such as when working on a circuit board), you want a microscope with a large depth of field, which allows you to do just that–focus on things on different planes at the same time.
Generally, the higher you magnify an image, the smaller the depth of field becomes, and the less you magnify an image, the greater the depth of field becomes.
11. What is the focal distance of a microscope?
The focal distance, or working distance, of a microscope is the distance at which the objective lens has to be in relation to the sample that you wish to view in order to achieve a focused image. Remember, this is the distance between the objective lens and the surface of the sample, not of the table. So if you have a 3″ tall sample and a microscope objective lens that has a 4″ focal distance at 7x magnification, you need to be able to move that microscope head up to 7″ away from the table (so 4″ above the 3″ sample’s surface) in order to focus.
The rule is, the higher the magnification of a lens, the closer it needs to be to achieve focus, and the less it has, the farther away you need to be to focus.
12. What is a Diopter adjustment on a microscope used for?
Many individuals have eyes with differing strengths or focal points. A Diopter adjustment helps compensate for those. On a binocular or trinocular microscope, the Diopter will be located on either the right ocular tube, or both ocular tubes. What it does is telescopes the eyepieces towards you or away from you (into the microscope) to compensate for your individual, unique eyes.
If you have a fixed eyepiece and 1 Diopter, focus the microscope, then look into it with the eye that is on the fixed ocular tube side (typically right). From there, look in with the opposite eye, and adjust the Diopter until the adjustable eye becomes focused. That’s all there is to it!
If you have two adjustable Diopters, follow the same process–set one dead center in the travel range, and adjust the other until both are clear. You may need to go back and forth adjusting, which is fine. Just take your time to be sure it’s correct for you to avoid eye strain and headaches!
You can also use the Diopter adjustment to help collimate the image–basically, making the two circles of the image from each eye appear to be one. So if each eye seems to see an individual image, give this an adjustment.
13. What is a mechanical stage?
A microscope stage on a compound microscope has to move vertically up and down in order to achieve focus, so it is too simplistic to say a mechanical stage is one that moves, however, a truly mechanical stage will also move in the X and Y dimensions via two knobs in order to allow a user to scan through a sample, or easily center it in the field of view without touching it by hand.
Touching a slide by hand is both cumbersome, clumsy, and can leave oils that disturb the image you’re trying to view, so mechanical stages are highly sought after in a quality microscope.
14. Why do I need to start with the lowest magnification setting when using a microscope?
The lowest magnification setting has the largest field of view, so it is the easiest to locate your microscopic sample and center on it. It’s also the easiest to focus, so you can start there, then change the objective to the next higher, refocus, recenter, and repeat until the desired magnification setting is achieved.
If you are a microscope veteran and can immediately focus and scan on higher magnification values, go for it. There’s no hard and fast rule that says you HAVE to start at 4x or lower. But, it’s just easiest to most novices to start that way, so we recommend doing so also.
15. What is better, LED or halogen?
There isn’t a solid answer here, as it’s mostly personal preference, but in general, it depends on your application (like most things microscopy related).
Halogen bulbs are common in microscopy because the bulbs are cheap, are replaceable, and provide close to natural sunlight (even more so with a daylight blue filter), however, they emit a great deal of heat when used, which can limit how long you can view a liquid or heat sensitive sample before it becomes dried up and dies, and the bulbs do burn out, so they have to be replaced rather frequently depending on how oftena nd how long you use a microscope for.
LED bulbs are used frequently these days due to its extremely long lasting nature, low power draw, and lack of heat emission, however, generally these are soldered onto a board of their own in order to function, and often are a bright white light that can slightly discolor samples instead of the natural sunlight yellow of a halogen.
If for any reason it does malfunction (rare, but it does happen), instead of getting 40,000+ life hours of use in your LED microscope, it will likely need to be sent back for warranty service, or you will need to learn how to solder to take it apart and repair yourself. If you’re capable of doing this, I’d say always go for the LED. It really isn’t hard–a YouTube video or two, some solder, and a soldering iron, and you’ll be all ready to rock (even more so if you have a stereomicroscope to help do the job!)
So, if you need to take color true images, or want to be sure you can always replace your bulb easily, go with a halogen lit microscope. If you have a sample that is heat sensitive, or you need longer viewing time with it, go for an LED microscope.
Bonus Question: What is empty magnification, and why should I use/avoid it?
Empty magnification is when a microscope achieves higher than 1000x magnification by using an eyepiece of greater strength than 10x. The problem here is that when you use an eyepiece to increase magnification, you do not increase optical resolution (which is, in layman’s terms, the level of detail in an image measured by how small of an object you can see). Only by changing objectives can you increase optical resolution, and above 100x does not exist at this time due to limitations set by the rules of physics (how much light can be prevented from scattering, and how curved a lens can be to still create an image that the eye can see, etc).
So, getting a microscope above 1000x might feel snazzy, but really, it isn’t as cracked up as it sounds. Above 1000x, you will enlarge an image of something, but not add any detail. For an example, save or open a picture on your computer, and use the magnifying tool to zoom in. You don’t see more detail, but it gets bigger. You eventually will start seeing pixels, or the little bits that make up the picture. You lose detail–the digital resolution isn’t high enough to show you what you want to see at the level of detail you want. Same concept when using a stronger eyepiece–it’s like clicking that magnifier tool.
Now, if you have a small structure that you CAN resolve at 1000x that you want to see larger, using above a 10x eyepiece will help with that. Great for kids if you want to point to a specific structure and make it easy for them to see. Pointers in eyepieces help with this too, however, that would be the only benefit you get from using greater than a 10x eyepiece. So, while it’s not all that most places advertise as being the best thing since sliced bread, it still DOES help. Many enthusiasts write off all magnifications above 1000x, but they’re still useful to a lesser degree.
For further reading, feel free to check out our Microscope Basics educational center, or just start reading our reviews to find what microscope works best for you! If you need a hand, feel free to Contact Us for help. We are always just an email away!