USFCLASS is reader-supported. When you purchase through links on our website, I may earn an affiliate commission.*

Eyepiece for a scope: Everything you need to know

One of the major components of scope is an eyepiece. It’s the part closest to the eyes, hence the name eyepiece. When you look through the scope lens, you’re looking through the eyepiece.

But why is an eyepiece important? What are the different types of eyepiece scopes?

Understanding the eyepiece and how to choose the right one is important. It combines with the field scope body to determine magnification. If you’re looking to purchase an eyepiece, then you must understand the various types and their purposes.

Keep reading below as we break down everything you need to know about eyepieces.

Eyepiece scope definition

An Eyepiece scope is a type of lens found on the scope or an optical device like a microscope or telescope. It’s the lens closest to the eyes when you look through an optical device.

The other lens on the scope is the objective lens and is larger in size. An objective lens will collect light, bring it into focus, and create an image. The eyepiece is very close to the focal point of the objective lens to help magnify the image.

An eyepiece construction usually features many lenses in a housing. There is a barrel on one end with a unique shape to fit the scope.

When focusing on an image, you can move the eyepiece closer or further away from the objective lens. But most optical devices feature a focussing mechanism to move the eyepiece shaft without moving the eyepiece.

Generally, an eyepiece is important since it affects magnification. Different eyepieces have different focal lengths which affect magnification. In addition, the sharpness and clarity of the image are affected by the eyepiece quality.

The size of the eyepiece lens can also affect the field of view. Choosing the right eyepiece lens is important if you want the best view possible.

Types of Eyepiece Scopes

Eyepiece scopes come in different designs. Each of the designs comes with its own weaknesses and strengths. There are three main types of eyepiece scopes based on the optical design:

Refractor eyepiece scope

A refractor eyepiece scope is a type of telescope that uses lenses to gather and focus light. The lens at the front of the telescope, called the objective lens, gathers and refracts (bends) the light. The eyepiece lens then magnifies the image and brings it into focus for the observer. 

Refractor eyepiece scopes are popular for their relatively simple design, ease of use, and good optical performance. 

It’s a unique type of eyepiece that comes in a variety of sizes and designs. You can choose from small, portable models to large, professional-grade instruments used in astronomy research.

Reflector eyepiece scope

A reflector eyepiece scope on the other hand is a type of telescope that uses mirrors to gather and focus light. It features a primary mirror at the bottom of the telescope that reflects the light to a secondary mirror.

The secondary mirror is located near the top of the tube. It in turn reflects the light to the eyepiece located on the side of the telescope. 

Reflectors are popular for their large apertures. They are well-suited for deep-sky astronomy, and they are often used by amateur and professional astronomers alike. Reflectors can come in a range of sizes and designs just like refractors. 

Shooters can choose from small, portable models to large. There are also sophisticated instruments with computerized tracking and imaging capabilities.

Overall, reflectors can be more complicated to set up and use than refractors. But they tend to offer better performance in certain applications.

Catadioptric eyepiece scope 

A catadioptric eyepiece scope is a type of telescope that uses a combination of lenses and mirrors to gather and focus light. The two most common designs are the Schmidt-Cassegrain telescope (SCT) and the Maksutov-Cassegrain telescope (MCT). 

In both designs, a corrector lens at the front of the eyepiece is used to reduce optical aberrations, and a spherical or ellipsoidal mirror at the back of the telescope reflects the light back through a hole in the center of the primary mirror. 

The light is then reflected by a secondary mirror and directed to the eyepiece located at the back of the scope. Catadioptric eyepiece scopes are popular for their compact design, which makes them portable and easy to set up, while still offering good optical performance. 

They are well-suited for a wide range of observing applications. However, they can be more expensive than other types of eye scopes. But they generally offer a good balance of performance, convenience, and versatility.

You can easily interchange all three eyepieces to vary the magnification and field of view of the image. The choice of telescope type and eyepiece depends on the specific needs and preferences of the observer.

Eyepiece Scope Components

  1. Objective lens: The objective lens is the main lens of the eyepiece that collects and focuses the light. The size and quality of the objective lens will affect the clarity and brightness of the image.
  2. Focuser: The focuser is the mechanism that allows the observer to adjust the distance between the eyepiece and the objective lens, thereby bringing the image into focus. A smooth, precise focuser is important for comfortable observing and accurate focusing.
  3. Eyepiece: The eyepiece is the lens that magnifies the image and brings it into focus for the observer. Eyepieces come in a range of focal lengths and designs, and choosing the right eyepiece is important for achieving the desired magnification and field of view.
  4. Mount: The mount is the support structure for the eyepiece and allows it to be pointed and tracked accurately. A stable, sturdy mount is important for smooth, shake-free observing.

How to Choose an Eyepiece Scope

When choosing an eyepiece scope, consider the following factors:

  • Purpose of use: Think about the type of observing you plan to do. Do you want to observe targets at long-range or short-range? Different types of eyepieces are better suited for different types of observation.
  • Magnification and aperture: Consider the magnification and aperture of the eyepiece. Magnification is determined by the focal length of the eyepiece and the focal length of the eyepiece. A larger aperture allows for higher magnification and better detail.
  • Portability and ease of use: Think about how portable and easy to it is. If you plan to take it with you on the go, a smaller, more portable eyepiece may be a better choice. Consider the weight and size of the eyepiece, as well as the ease of setup and use.
  • Price range: Finally, consider your budget. Eyepieces can range in price from a few hundred dollars to several thousand. Set a budget and look for the best eyepieces within that price range. Remember that quality is important.

How to Use an Eyepiece Scope

Here are some basic steps for using an eyepiece scope:

  1. Set up and alignment: Choose a level, stable surface to set up the eyepiece scope. Make sure the mount is properly assembled and secure. Align the eyepiece until the object is centered in the eyepiece.
  2. Focusing: Adjust the focus knob until the image in the eyepiece appears sharp and clear. Use a high-power eyepiece to fine-tune the focus if necessary.
  3. Adjusting magnification: Change the magnification of the eyepiece scope by swapping out eyepieces with different focal lengths. Higher magnification eyepieces will produce a smaller field of view and require more precise tracking of the object being observed.
  4. Tips for observation: Take your time observing and allow your eyes to adjust to the darkness. Use a red light flashlight to help preserve your night vision. Look for patterns and details in the objects you observe, and consider sketching what you see. Take breaks and allow your eyes to rest to avoid eye strain.

Maintenance and Care of Eyepiece Scopes

Proper maintenance and care of your eyepiece scope will help keep it in good condition and extend its lifespan. Here are some tips for cleaning, storage, and damage prevention:

  • Cleaning the lenses: Only clean the lenses of the eyepiece with a soft, lint-free cloth or lens-cleaning tissue. Do not use regular paper towels or tissues since they can scratch the lenses. You also need to avoid touching the lenses with your fingers as oils from your skin can leave marks.
  • Proper storage: Store the telescope in a dry, dust-free location, such as a closet or storage case. Cover the eyepiece with a protective cover or case to prevent dust buildup and scratches.
  • Preventing damage: Handle the telescope and its accessories with care. Always use the included covers for the lenses and eyepieces to prevent damage. Avoid exposure to extreme temperatures or moisture. These elements damage the optics and cause mold or fungus growth.


Choosing the right eyepiece scope is important for achieving the best viewing experience. It is important to consider the purpose of use, magnification, aperture, portability, budget, and ease of use.

Once you have chosen your eyepiece scope, proper maintenance and care, including cleaning the lenses, proper storage, and damage prevention, will help extend its lifespan and ensure it remains in good condition.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top