Helpful Guide for Everything to Know About Microscope Eyepieces
Ever wonder what the role a microscope eyepiece plays in the microscope’s optical system? It might surprise you to learn it’s more than just where you view your specimen. In this article we review everything about microscope eyepieces.
What is the eyepiece of a microscope?
Microscope eyepieces hold the lenses you use your eyes to look through. They sit atop the optical tube. A compound microscope has one or more eyepieces that can be changed or swapped to other compatible sized eyepieces.
Depending on the lens assembly and the scientists who designed them, the eyepieces have different names, such as:
- Huygenian eyepiece
- Ramsden eyepiece
- Kellner eyepiece
When using a microscope, does light enter through the eyepiece first?
Surprisingly, the answer is no. The eyepiece happens to be the last part in the path of light!
- First, light comes up through the specimen and objective lenses.
- Then the light passes through the eyepiece system.
- Finally, that same light travels straight to your eye.
What does the eyepiece do on a microscope?
The eyepiece is one half of the optical system. It lets you see the object with a magnified view. The other half of the optical system is the objective. The combination of the eyepiece and the objective provides you with the total magnification.
What does the ocular lens do on a microscope?
In microscopy, ocular lenses are typically referred to as eyepieces. Ocular refers to your eye, so it’s an alternative way to explain where to place your eye on the lens system to view the specimen.
What does WF mean on an eyepiece?
WF on a microscope eyepiece means wide field. The field of view or how much area you can see through the eyepiece is extra wide. Better optical designs, more lenses, or larger diameter lenses increase the field of view.
What is the magnification of the eyepiece?
When you want to know how much the eyepiece of a microscope magnifies a specimen, you can check each eyepiece for a number followed by an X. For example, if you see 10X written on the eyepiece, it provides 10x magnification.
However, keep in mind, 10x is NOT the total power of the microscope. To know the total power of a microscope, multiply the eyepiece power by the objective power. Most eyepieces are 10X or 16X which provides plenty of power for optical microscopes.
How many eyepieces are on your microscope?
If there are two, that’s called a binocular microscope or binocular head microscope and the eyepieces should have matching magnification power.
How many eyepieces does a monocular microscope have?
As you may have surmised from its name, a monocular microscope has only one eyepiece.
How to find eyepiece field number (FN)?
Before finding the field number, let’s learn what a microscope field number is. The field number (FN) is the diameter of the range that can be seen through the eyepiece. The final area depends on the objective lenses as well, but the field number lets you know the capability of the eyepiece itself.
So, where can you find the FN? It’s written on the side of the eyepiece usually followed by mm for millimeters.
What is the field of view on a microscope?
If you want to know the total field of view on a microscope, you first need to find the field number of the eyepiece, written on the side of the eyepiece in mm or millimeters.
The higher the number, the wider the field of view for that eyepiece. If you need a wider field of view, you can switch it out for a wider eyepiece with a higher field number. The field number is not the same as the focal length of the eyepiece. It only refers to the size of viewable area, and focal length is another way to calculate the power it can magnify.
Calculate the magnification power by taking that field number and divide it by the magnification of the objective lens. That gives you the field of view in millimeters, so when you look at a sample through the optical system of the microscope, you can see (at most) that many millimeters across in size.
To better clarify: if the specimen/object you wish to inspect is 2 mm but your total field of view is only 1 mm, you will not be able to see your entire specimen/object at once.
What is the eye relief of an eyepiece?
Eye relief is the ideal distance from the outside surface of the eyepiece to your eye, so your image is maximized in size. Microscopes with long eye relief tend to be more comfortable, as you don’t have to place your eye right up to the eyepiece. Instead, you can sit back a bit more. The optics involved in achieving longer eye relief are more complex and usually more expensive. If you wear glasses and you don’t want to remove your glasses when viewing through the microscope, it’s helpful to have a microscope eyepiece with long eye relief.
How do you clean a microscope eyepiece lens?
Using a slightly damp microfiber cloth is the best way to clean microscope eyepieces. Be sure to clean the outer surfaces and inner surfaces to remove any dust. Do not use any abrasives, alcohols, ammonia or other harsh or unknown chemicals.
How can you adjust microscope eyepieces?
Adjusting eyepieces isn’t always possible. It depends on the microscope. If you have a knob between the two tubes and eyepieces on a binocular head, that’s known as a diopter adjustment. You can adjust the focus from the left eyepiece to the right eyepiece using the diopter adjustment. This is similar to how many, not all, binoculars work as well.