How to choose telescope eyepieces
Updated June 2026Independently researchedNo paid placement.
For most backyard astronomers, the best eyepiece upgrade is a modest set of three or four well-chosen focal lengths from a reputable brand, starting with a comfortable low-power wide-field option and a higher-power planetary eyepiece. Focus on eye relief, apparent field of view, and barrel size (1.25-inch vs. 2-inch) rather than chasing the most expensive glass. A good rule: spend roughly the same on eyepieces as you did on your telescope, and buy from brands with solid return policies.
What should you look for in a telescope eyepiece?
Start with the barrel size: most beginner scopes take 1.25-inch eyepieces, while larger Dobsonians and some refractors also accept 2-inch barrels for ultra-wide views. Check your telescope’s focuser and any included adapter before buying. Focal length (in millimeters) determines magnification when paired with your scope’s focal length, divide the telescope’s focal length by the eyepiece’s focal length to get power. Beyond focal length, pay attention to eye relief (the distance your eye needs to be from the lens) and apparent field of view (how wide the view feels). Long eye relief is crucial if you wear glasses. A wider apparent field (typically 60° to 80°) makes objects easier to find and more immersive, but often costs more. Also consider the eyepiece’s optical design, Plössl, Erfle, and modern multi-element designs each have trade-offs in sharpness, color, and price.
How many eyepieces do you really need?
Most observers do fine with three or four focal lengths that cover low, medium, and high power. For example, with a typical 1000mm focal length scope, a 25mm eyepiece gives about 40x, a 10mm gives 100x, and a 5mm gives 200x, though the exact numbers depend on your scope. A low-power wide-field eyepiece (around 20–30mm) is great for star clusters and nebulae, a mid-power (10–15mm) works for the Moon and bright planets, and a high-power (5–8mm) for planetary detail. Avoid buying a huge set of cheap eyepieces; you’ll rarely use most of them. Instead, invest in fewer, higher-quality pieces. Many experienced observers recommend starting with a good 25mm and a good 10mm, then adding a 2x Barlow lens to double your options. A Barlow effectively gives you two magnifications per eyepiece, but note that it can reduce image brightness and may not work well with very short focal length eyepieces.
What do the numbers on an eyepiece mean?
The main number is the focal length in millimeters, shorter numbers give higher magnification. The second key spec is the apparent field of view, often listed as degrees (e.g., 50°, 68°, 82°). A wider apparent field shows more sky at a given magnification, making it easier to track objects. The barrel size (1.25-inch or 2-inch) affects how much light can pass through and the maximum field of view possible. Eye relief is measured in millimeters and tells you how far your eye should be from the lens. Long eye relief (15mm or more) is essential for eyeglass wearers. Some eyepieces also have a twist-up eyecup to adjust eye relief. Finally, the number of lens elements (e.g., 4-element Plössl vs. 6-element wide-field) gives a hint about optical complexity, but more elements don’t automatically mean better, coatings and quality control matter more.
Are expensive eyepieces worth the money?
For most hobbyists, a mid-priced eyepiece from a reputable brand (like Celestron, Explore Scientific, or Tele Vue) will deliver excellent views without breaking the bank. Expensive eyepieces often offer wider apparent fields, better edge sharpness, and more consistent eye relief, but the difference is subtle at low power. At high power, premium eyepieces can reduce chromatic aberration and provide sharper planetary detail, which may matter if you observe the Moon and planets often. However, the law of diminishing returns kicks in quickly. A budget-friendly eyepiece that costs a fraction of a premium model might be 90% as good in most scopes. The best value lies in mid-range lines that offer multi-coated optics and decent eye relief. Also consider buying used from reputable astronomy forums, many enthusiasts upgrade frequently, and you can get premium glass for less.
How do you choose between 1.25-inch and 2-inch eyepieces?
The choice depends on your telescope’s focuser and what you want to observe. Most telescopes come with a 1.25-inch focuser, which is perfectly adequate for magnifications above about 60x. If you want ultra-wide, low-power views (e.g., to fit the entire Pleiades or Andromeda galaxy in one field), a 2-inch eyepiece with a long focal length (like 30mm or 40mm) can give a much larger true field of view. Check if your focuser has a 2-inch adapter, many do, even on budget scopes. If not, you can buy an adapter, but it adds cost and may not be worth it unless you plan to observe large nebulae or clusters. For planetary and lunar viewing, 1.25-inch eyepieces are usually sufficient and offer more variety at reasonable prices. Remember that 2-inch eyepieces are heavier and may require a stronger focuser or a counterweight on some mounts.
What are the best eyepiece brands for beginners?
For beginners, brands like Celestron, Orion, and Meade offer reliable, affordable eyepieces that work well with entry-level telescopes. Celestron’s Plössl and Omni series are classic choices, while Orion’s Sirius and Edge-On lines provide good eye relief and sharpness. Explore Scientific and Tele Vue are premium brands known for exceptional wide-field performance, but they come at a higher price. If you’re on a tight budget, consider brands like SVBONY and Agena Astro, they offer surprisingly good performance for the price, though quality control can vary. Read recent owner reviews on cloudynights.com or the r/telescopes subreddit to see what’s currently well-regarded. Avoid generic no-name eyepieces from marketplaces; they often have poor coatings and inconsistent quality. A good rule: stick with brands that have been around and have a customer service reputation.
Frequently asked questions
What is the best eyepiece for viewing planets?
For planets, you want a high-power eyepiece with good contrast and sharpness, typically a focal length that gives 150x to 250x with your scope. A 6mm to 9mm Plössl or a premium planetary eyepiece like a Tele Vue Delos works well. Look for long eye relief and multi-coated optics to reduce glare.
Can I use any eyepiece with my telescope?
Most telescopes accept 1.25-inch eyepieces, but some older or very small scopes use 0.965-inch, and larger scopes may also take 2-inch. Check your focuser diameter and whether you have an adapter. Also ensure the eyepiece’s focal length gives a reasonable magnification, too high a power can exceed your telescope’s useful limit (about 2x the aperture in millimeters).
Do I need a Barlow lens?
A Barlow lens is a handy way to double your eyepiece collection without buying more eyepieces. A 2x Barlow effectively turns a 25mm eyepiece into a 12.5mm, and a 10mm into a 5mm. However, it adds an extra element that can slightly reduce contrast, and with very short focal length eyepieces, the eye relief may become uncomfortably short. Many beginners find a Barlow useful, but a dedicated short-focal-length eyepiece often performs better.
What does eye relief mean and why does it matter?
Eye relief is the distance from the eyepiece’s top lens to where your eye should be to see the full field. If you wear glasses, you need at least 15mm of eye relief to avoid scratching your glasses and to see the entire view. Long eye relief is also more comfortable for extended observing. Some eyepieces have adjustable eyecups to help position your eye.
Are 2-inch eyepieces always better?
No. 2-inch eyepieces are only better for low-power, wide-field views, they allow a larger true field of view than 1.25-inch eyepieces. For high-power planetary viewing, a 1.25-inch eyepiece is just as good and often cheaper. Also, 2-inch eyepieces are heavier and may require a stronger focuser. Only invest in 2-inch if your scope supports it and you observe large deep-sky objects.
How do I clean my eyepieces?
Use a soft brush or air blower to remove dust, then a microfiber cloth with a drop of lens cleaning solution if needed. Never use paper towels or harsh chemicals. Avoid touching the glass with your fingers. Store eyepieces in a padded case with caps on to prevent dust and scratches. Clean only when necessary, over-cleaning can damage coatings.