Telescope Eyepiece

Beginner in astronomy often gets confused when it comes to choosing eye-piece for telescope. As eye-piece is one of the important telescope accessory that contributes to your sky watching experience you need to choose it carefully.If you don’t research well then you’ll end up purchasing excessive lenses which you don’t need. There are various eyepiece design and lenses that vary for different viewings. Depending on your budget and the viewing needs you need at least 3-4 eyepiece and not more than that. In this hub you’ll be learn about different types of eyepiece.

Types of Eyepiece Designs:

• Erfle Telescope Eyepiece
• Plossl Telescope Eyepiece
• Orthoscopic Telescope Eyepiece
• Kellner Telescope Eyepiece
• Ramsden Telescope Eyepiece
• Huygens Telescope Eyepiece

Erfle Telescope Eyepiece - This eyepiece design gives sharp deep sky view at low powers. High Magnification could distort the sharp image in some telescope designs if corrective measures are not taken. This eyepiece makes use of 5-6 elements in it’s design.

Plossl Telescope Eyepiece - This design provides sharp image quality and an apparent field of view of about 50 degrees. It is also one of the popular and most used eyepiece design. It uses 4-5 elements in it’s design and have wider view than orthoscopic lenses. They’re inexpensive and cost about 50$-150$.

Orthoscopic Telescope Eyepiece - Orthoscopic eyepiece is used in small telescope or general purpose telescope for kids. It uses 4 elements in it’s design and is sufficient for the planetary viewing. Cost of these lenses ranges from 40$-100$.

Kellner Telescope Eyepiece - This is 3 element eyepiece design and 40-45 view that gives you sharp and high quality image at low power. It is preferred for small to medium optical telescopes.

Ramsden Telescope Eyepiece - This is 2 element design with very narrow fields of view. They’re used for cheap telescope designs. They cost between 25$-40$.

Huygens Telescope Eyepiece - This is simple, 2 element design with very narrow field of view. This eyepiece is usually preferred by amateurs. They cost between 25$-45$.


Eyepiece Design sorted by Barrel size

Standard sizes of eyepiece are : .965", 1.25" and 2".

Note : Size of the eyepiece has nothing to do with the quality. Sharpness and clarity varies as per size and design of eyepiece. Avoid making purchase of these eyepiece with markings : H25mm, H20mm, H12.5mm and SR4mm.


The size .965“ is now obsolete and no longer used for professional telescope. But some small telescopes and entry level telescope still makes use of this lens. The 1.25“ size is the most commonly used eyepiece size for amateur telescopes. Professional astronomers use 2“ size eyepiece in their optical telescope. The size 2“ eyepiece is expensive and beginners in astronomy rarely need this lens. Depending on the type of telescope you’ve purchased the barrel size available to you’ll vary.