What are the Different Parts of a Telescope?

Stargazing, an activity that involved taking a closer look at heavenly bodies like the moon and other planets in the solar system, wouldn’t be possible without using a telescope. If you are fascinated by planets and stars, then you should already have a telescope that is ready to use at home or outdoors. 

However, do you know what the different parts of a telescope are and their purpose? If you don’t, then here are the things you need to know about the different parts of a telescope so that you will have a better understanding of how the device works.


A telescope eyepiece allows an observer to see a magnified image of the object being viewed. It is a small optical device that is inserted into the telescope’s focuser and is responsible for producing the final magnified view. 

Eyepieces are available in a variety of focal lengths and designs, each with a unique viewing experience. Some eyepieces offer a wider field of view, while others provide a more detailed and magnified view. 

telescope eyepiece

Telescope eyepieces come in different models, such as Huygenian, Plossl, Kellner, Erfle, ultrawide and orthoscopic.

The Huygenian eyepiece is composed of two lenses, one convex and one concave, which work together to magnify the image seen through the telescope. It has a relatively narrow field of view compared to other eyepieces, but it is known for its sharp and clear images.

The Plossl eyepiece is known for its high-quality construction, excellent image quality, and relatively low cost. It typically offers a wide field of view and a long eye relief, making it comfortable to use for extended periods of time.

A Kellner eyepiece is a type of ocular lens designed for use in telescopes. It features a three-lens design, consisting of a positive doublet lens and a negative singlet lens, which is meant to provide good visual clarity and a wider field of view.

The Erfle eyepiece offers a relatively wide field of view and is typically used for low- to medium-magnification observations. It is popular among amateur astronomers because of its relatively low cost and high-quality image.

telescope on viewdeck

An ultrawide telescope eyepiece is a type of eyepiece designed for telescopes that offers a significantly wider field of view than traditional eyepieces. These eyepieces typically have a wider apparent field of view, typically around 70-100 degrees, which allows for a more immersive and expansive viewing experience.

An orthoscopic telescope eyepiece is a type of optical instrument that is commonly used by astronomers and amateur stargazers to observe celestial objects. This eyepiece is designed to provide a high-quality image with minimal distortion, making it an ideal choice for those who are interested in exploring the night sky. Unlike other types of telescope eyepieces, the orthoscopic eyepiece uses a four-lens system to produce a clear image that is free from aberrations and other visual artifacts.


A finderscope is a small auxiliary telescope that is mounted on top of a larger main telescope. Its primary function is to help locate objects in the sky that are too dim to be seen with the naked eye. 

A finderscope typically has a much wider field of view than the main telescope, allowing the observer to easily locate celestial objects before fine-tuning their position using the main telescope. They also often feature reticles or crosshairs to aid in alignment and centering of the object being observed.

telescope with a finderscope at the top

The size of the finderscope is determined by the aperture of the lens and the magnification power.

For amateur astronomers looking to improve their aiming accuracy, a 6×30 finderscope is considered the minimum useful size for a magnifying finderscope on a telescope. This size provides a magnification of six times the naked eye and a 30mm aperture, which allows for a brighter image. However, for those seeking more precise targeting, an 8×50 or larger finderscope is preferable.

The larger aperture and magnification provide a clearer image, making it easier to pinpoint specific celestial objects.

Objective Lens

An objective lens is a key component of a telescope that is responsible for gathering and focusing light from distant celestial objects. It is usually a convex lens that is situated at the front of the telescope, facing the sky. The lens collects and bends light, directing it towards the eyepiece, where the image is magnified and brought into focus for observation. 

objective lens on a telescope

The quality and size of the objective lens are crucial in determining the performance and capabilities of the telescope. The larger the lens, the more light it can gather, resulting in a brighter and more detailed image.

Telescope Tube

green telescope tube

A telescope tube is a cylindrical housing that contains the optical components of a telescope, including the objective lens or mirror and the eyepiece. The tube serves to protect the delicate optics from dust, moisture, and other environmental factors that can degrade their performance. It is also designed to reduce internal reflections, which can cause unwanted glare and reduce the contrast of the image. 

The length and diameter of the tube are critical factors in determining the telescope’s magnification, resolution, and light gathering power.

Structural Support 

Telescopes are also built with structural support components, such as the mount and tripod. The mount is designed to hold the telescope and allow it to move in a controlled manner to track the movement of celestial objects in the night sky. The tripod provides a stable platform that allows the mount to move smoothly and accurately. 

The mount and tripod come in a variety of designs and materials, with some being more suitable for certain types of telescopes or observing conditions. The two components work together to provide a comfortable and stable viewing experience. 

telescope tripod

The most commonly used telescope mounts are the Altazimuth mount and Equatorial mount. Altazimuth mounts are suitable for beginners as they are easy to use and move in both horizontal and vertical directions. 

Equatorial mounts, on the other hand, are more complex but allow for smooth tracking of celestial objects due to their ability to move in sync with the Earth’s rotation. 

Other types of mounts include Dobsonian mounts, which are sturdy and suitable for large telescopes, and German equatorial mounts, which are popular among astrophotographers due to their precise tracking capabilities.


A telescope mirror is a specialized optical component that plays a critical role in the functioning of a telescope. It is typically a curved reflective surface that is carefully designed and crafted to gather and focus light from distant objects in the universe. The mirror is the primary light-gathering element in a telescope and is responsible for capturing and reflecting the light that enters through the telescope’s aperture.

reflecting telescope

Mirrors are a crucial component of reflecting telescopes, which are used to observe celestial bodies during space exploration. Unlike refracting telescopes, which use lenses to bend and focus light, reflecting telescopes use mirrors to gather and reflect light to produce images. 

The primary mirror in a reflecting telescope is typically a concave shape, which collects and focuses the incoming light onto a secondary mirror or lens. This arrangement allows for larger apertures and greater light-gathering capabilities, which are necessary for observing faint objects in space.


Understanding the different parts of a telescope is crucial for anyone interested in astronomy or stargazing. The three main parts are the objective lens or mirror, the eyepiece, and the mount. The objective lens or mirror collects and focuses light, the eyepiece magnifies the image, and the mount keeps the telescope stable and allows for easy adjustments. By knowing how each part works, you can choose the right telescope for your needs and get the most out of your stargazing experience.