One of the most overlooked upgrades in amateur astronomy is the eyepiece. Many beginner telescopes ship with mediocre included eyepieces that significantly underperform the optical tube they’re attached to. As a former astronomy teacher who has tested dozens of eyepieces, here’s what you need to know and what to buy.
Why Eyepieces Matter So Much
Your telescope’s objective lens or mirror gathers and focuses light. The eyepiece then magnifies that focused image and presents it to your eye. A poor eyepiece can blur, distort, and narrow the image from an otherwise excellent telescope. A great eyepiece maximizes every photon your telescope collected. Upgrading eyepieces is often the highest return-on-investment improvement you can make to an existing telescope.
Key Eyepiece Specifications Explained
Focal Length (mm)
The focal length printed on an eyepiece (e.g., 25mm, 10mm, 6mm) determines magnification when combined with your telescope’s focal length. Magnification = telescope focal length ÷ eyepiece focal length. A 25mm eyepiece in a 1000mm focal length telescope gives 40x magnification. A 10mm eyepiece gives 100x. Lower mm = higher magnification.
Apparent Field of View (AFOV)
This is how wide the circle of sky you see appears — typically between 40° (narrow) and 100° (ultra-wide). Wider fields feel more immersive and make finding objects easier. Wide-angle eyepieces (65°+) are more expensive but dramatically more enjoyable to use.
Eye Relief
The distance from the eyepiece lens to where your eye should be positioned. Short eye relief (less than 10mm) is uncomfortable for glasses wearers. If you wear glasses while observing, look for eyepieces with 15–20mm+ of eye relief.
Top Eyepiece Picks for 2026
Best Budget: Celestron Plossl Series (~$20–$35 each)
Plossl eyepieces are the workhorse of amateur astronomy. The 4-element Plossl design produces excellent central sharpness and good contrast at a very accessible price. The Celestron Plossl series covers focal lengths from 6mm to 40mm, giving you a range of magnifications for different targets. A 25mm Plossl and a 10mm Plossl will cover most observing situations. The main limitation is the narrow 50° apparent field of view, which makes them feel tunnel-like compared to wider designs.
Best Mid-Range: Explore Scientific 82° Series (~$70–$120 each)
The Explore Scientific 82° eyepieces offer a dramatically wider field than Plossls at a fraction of the cost of premium brands. Looking through these after a basic Plossl is like opening a window compared to a porthole. The 24mm, 11mm, and 6.7mm focal lengths cover low, medium, and high magnification across most telescope configurations. Fully multi-coated optics produce bright, high-contrast views. Excellent eye relief across the range makes them comfortable for glasses wearers.
Best Premium: Televue Nagler or Ethos Series (~$200–$400 each)
Televue Nagler and Ethos eyepieces are the gold standard — many amateur astronomers describe their first look through a Nagler as a transformative experience. The ultra-wide apparent fields (82° for Naglers, 100° for Ethos) create the sensation of floating in space. Optical sharpness and contrast are superb across the entire field. These are lifetime investments — many astronomers use the same Nagler eyepieces across multiple telescopes over decades. If budget allows, a Nagler 17mm or Ethos 13mm is a purchase you’ll never regret.
Which Focal Lengths Should You Buy First?
For most beginners with a telescope in the 700–1200mm focal length range, I recommend starting with three eyepieces covering low, medium, and high magnification:
- 25mm or 32mm: Low power, wide field. For finding objects, star clusters, large nebulae, and the full Moon disc.
- 12mm or 15mm: Medium power. The most versatile magnification for planets, double stars, and smaller deep-sky objects.
- 6mm or 8mm: High power. For planetary detail on nights of steady seeing.
A Barlow lens (2x) doubles the effective magnification of any eyepiece, giving you six magnification options from three eyepieces — excellent value.
The Verdict
If you’re upgrading from a stock eyepiece, the Celestron Plossl series is the best starting point. If you’re ready to invest more, the Explore Scientific 82° series will genuinely transform your views. And if you want the very best, a Televue Nagler or Ethos will become your most treasured piece of astronomy equipment.
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