Magnification, Resolution, Lenses – We’re Going to Chat about it All.
Hello there, Friend, Let’s talk Microscopes! This is a question that I get quite regularly, especially when there is any story or picture that has us doing microscope work. The question usually is, “Do you like your microscope? Would you recommend it?”
The short answer is Yes! I love my microscope. I have an iOptron ST-80 compound microscope. It was around $100 when I purchased it. It’s currently around $79. It has served us well over these many years, and came with most, if not all, of the supplies that I needed, and some that maybe I didn’t, like the digital camera.
However, recommending it is a different question all together. You see, many of the people asking about my microscope are still schooling elementary-school-age children and a classic compound microscope might not be the best option. So, let’s shift the conversation to what you might think about when purchasing one.
In this Post you’ll find:
There are a good number of different types of scopes, from a compound microscope that most people are asking me about (and the one I have) to a dissecting scope, stereoscope, and more, but today we’re going to be discussing pocket microscopes or portable microscopes and the classic compound microscope. Some things that we want to consider in choosing a microscope:
- What we want to use the microscope for.
- What we want to view under the scope.
- The budget that we are working within.
- The magnification of the scope.
- If you want to view the image on a screen.
- If you want the scope to be portable.
- How long and how often you want to use the scope.
Pocket microscopes are portable microscopes that can be carried around in your pocket. They usually are plastic, have a magnification of 80 to 200x’s, which is a lower magnification, and are around $40. I’ve seen a couple advertise that have a magnification of up to 800x’s, but knowing what I know about lenses, depth of field, and magnification, I really doubt that the resolution is very good for that level of magnification. Personally, I’d stick with the lower magnifications for these. They are likely high quality in this range. Most work by displaying the magnified image on a screen such as a cell phone, but some have an eye piece to look into. I’ll leave a couple links to ones that have been recommended to me below in LINKS.
DEPTH OF FIELD, MAGNIFICATION, AND RESOLUTION
For good resolution, or basically the image projected to be clear and crisp, you need stability, especially for higher magnification. The depth of field, or how much of a plane is in focus, is decreased as you increase the magnification. That means that you need a greater stability for greater magnification. Otherwise, the slightest movement is going to make the picture look blurry. This is why the magnification of pocket microscopes are so low. It’s hand held or something similar which doesn’t offer a lot of stability.
Does this make a pocket microscope a bad choice? Not necessarily. It’s all dependent on what you plan to use it for. Often, it’s the best choice if you are looking to spend less than $50, have children in elementary school, and really just want to go explore nature and take a look at the micro view of the world. They have some that work with cell phone to display the image on a screen which is really nice for young children. It allows for everyone to see the same image at the same time which aids in discussion. If you tried to work with a lab partner with microscope work, you’ll know what I’m talking about.
They are also usually working with a top light source, meaning the light source is coming from the top, not looking through a thin piece of say a prepared slide from the bottom. This is perfect for the vast majority of things that will be explored in the younger years, which is anything that one happens to pick up – a bug, a butterfly wing, a leaf, even a water sample. Usually you are not thinly slicing a cross-section, staining it, and then mounting it on a slide in the younger years. There are are exceptions, but…
What if you are wanting something more though? Something with a little more magnification and something that will last throughout all of the educational years, even into high school. For that you’re going to need a compound microscope. Most of the compound microscopes that I see are around $100, they have anywhere from 40 to 1000x’s with the 1000’x area usually being oil immersion. This is where you take a drop of microscope oil on a prepared slide (with a cover) and use the highest magnified lens. Most people that I know, and general homeschoolers fall into this group, don’t bother using this level of magnification. If you are a science nerd though, it’s fun! All that to say, the usual magnification is around 600 to 700x’s in magnification. This still is much higher magnification than a pocket microscope. You’ll want one that is around 400x’s.
One of the things that I look for in a compound scope is the number of lenses and the magnification of those lens. Mine has 10x and 16x eye piece, the lenses in the eyepiece that you look through, and a 4x, 10x, and 40x objective lens. These magnifications are multiplied depending on the lens that you use. For instance, if your eye piece lens is 10x and your objective lens is 4x, you will view a magnification of 40x. This variety of lenses gives you a great deal of versatility in the level of magnification that you can view. I also want my lenses to be glass. I don’t know that they are plastic yet in compound scopes; the good scopes aren’t that I know of, but glass is the way to go.
You want both a bottom source and a top source of light. Most have a bottom source of light and this is great for more transparent items like most prepared slides, but doesn’t work very well for opaque items such a coins, leaves, etc. If you only have a bottom source of light, you’re not going to be able to see those items very well. If you are spending that amount of money, you want full versatility that will allow you to view the most things, so you want a top light source as well. Mine uses a pen light, which is just enough light to help in viewing from the top.
Some of the compound scopes have a digital camera that projects the image onto a computer screen. I see this as very heavy plus when homeschooling. It’s nice to be able to see and talk about the same image with less confusing. My scope uses a webcam that fits into the monocular tube, the tube the eye piece fits into. The sacrifice here is in the magnification. It loses the magnification of the eye piece, but again, this doesn’t necessarily mean that it isn’t worthwhile, especially with younger children. I feel like the level of magnification is not quite as important than say when you are taking high school biology. I want to note that the photographs that you were seeing from my microscope are with my Canon 80D, a DSLR camera. They are not taken with the Webcam. Sometime ago I bought an adapter for my DSLR to hook up to my microscope and telescope.
A couple of other things to look for: clips on a stage, iris diaphragm, and illumination control. The stage is the part of the microscope that a slide sits on. It moves up and down when you focus the lens. When you focus the lens on a camera you are moving the lens to find the focal point. With a microscope, the lens stays stable and you move the stage closer or farther away from the lens to bring it into focus. This stage has a hole in the middle that the light comes through which is called an aperture on the microscope. It also should have two clips on either side of the aperature to hold your slide or specimen in place.
IRIS DIAPHRAM (APERATURE ADJUSTMENT)
On some microscope’s, below the stage you will have a wheel that has different size holes in it called the iris diaphragm or aperture adapter. This diaphragm helps to control how much light goes through the aperture so that you can more clearly see whatever it is that you are viewing. It works similarly to the iris of your eye. If your item is quite transparent, they are going to want a little less light coming through the bottom so it doesn’t wash it out in light. I wouldn’t say that this is imperative or a dealbreaker for the vast majority of people buying microscope’s with homeschooling. This is going to be an advantage to people that are going into science or are using this for higher level science classes, particularly biology or microbiology.
In addition to this at the base of some microscope’s where the light source is there’s a little wheel that can be adjusted that controls the brightness of the bottom source light. Distance a similar thing that the iris diaphragm does in helping to make the images clear as possible. Again, for the vast majority of people I don’t think this is quite as important as other aspects of the microscope, but if you see your child going into microbiology you might want to make sure it has these features.
The last feature that I want to talk about is focal adjustment. On the side of a microscope, you’ll have one or two knobs that you will move back-and-forth to move the stage up and down and focus your image in your lens. My microscope comes with one knob for focus. My preference is to have a course focus knob and fine focus knob. Again, it’s obviously not a dealbreaker because I purchased the one with only one knob. I just feel like it’s a little easier to get things into focus with the two knobs.
USING A MICROSCOPE
Finally, let’s chat a little bit about how to use a microscope. I’ve heard on more than one occasion that the manuals just kinda leave people hanging. Because of the very shallow depth of field they were looking at with higher level magnification, it helps to have whatever you’re looking at to be as thin as possible. Having said that, please don’t let this stop you exploring the world of magnification. Look at everything under the microscope!
The first thing to do is place your slide or your material over the aperture on your stage and clip it down with the clips. Then next thing that you want to do is make sure that you have all your objective lenses at the lowest level of magnification. The objective lenses are the ones just above the stage, not the ones that we look through with her eyes. On mine that’s 4x’s, and I’m just going to shift the lenses until I have it on the shortest lens which is also the lowest level of magnification.
From here we’re going to use either our one knob or our course knob to bring it into focus. If you have two knobs, you now use your fine knob to refine the image to an even better level of focus. You can stop here and enjoy the view.
If you want an even higher level of magnification, leaving everything in the microscope as is, shift the objective lens from the smaller to the next highest magnification. Usually this is the middle length lens. It will be going straight up and down so the trajectory is from the eyepiece through that lens and into the aperture at the stage. Then you will use the fine knob to bring it back into focus, or if you have one knob, just the one knob to bring it into focus. You just need to make sure that you bring the item into focus first with the lowest level of magnification and then working your way up in magnification. Otherwise, it’s pretty challenging to get your item in focus.
I always like to use my bottom source light. If you were looking at an opaque item, such as a coin, the bottom source is not very helpful, so you want to add that top source light as well. I also usually like to use my top source light in conjunction with my bottom source light. If you’re seeing a lot of bright light in your image and you think that would be better clarity if it wasn’t quite so bright, then you can start manipulating the light sources to clarify your image. On my microscope I have a talk like they can be turned off if I need to, as well as an iris diaphragm where I can choose the size of the iris and alter the amount of light coming through. I also have an illumination adjustment wheel at the bottom where my bottom light source is located where I can brighten or darken my light source.
And that’s it! If you have any questions, feel free to comment below. Don’t forget to consider looking at schools or universities when obtaining a scope They often are purging perfectly acceptable scopes when they purchase new ones. I hope that at least some of this is helpful to you finding a microscope that works for you. I’ll also leave a few links of microscopes and my favorite microscope accessories below.
My Microscope -iOptron ST-80
My Favorite Microscope Book
Another compound microscope recommended to me
A Recommended Micrososcope and Kit
A Portable Digital Microscope
DLSR Camera Adapter
Carson Pocket Microscope (recommended to me)
A Portable Digital Microscope
Just a note: I participate in Affiliates Programs. When you use some of the links above, your cost is the same, but I receive a very small commission from your purchase. For more information on my relationships see my Policies and Disclosures page.