While buying a telescope is undoubtedly the most significant purchase any amateur astronomer is likely to make, a plethora of accessories are available. Perhaps one of the most important of these is eyepieces. While the aperture of the telescope itself largely determines what you'll be able to see with it, eyepieces are a crucial part of that equation.
For those perhaps not familiar with them, eyepieces are the small hand-held lens that we place at the telescope's focus to bring the image into sharp focus for our eyes to observe. They are available in a variety of different types and designs. They also come in various focal lengths, determining the effective magnification. Focal lengths of anywhere between 3 to 50mm are widely available. Various lens designs are widely used — Plossl, Kellner, Orthoscopic and Radian are the most popular. Today, many companies also produce custom multi-element designs.
Eyepieces also come in different sizes in their barrel diameter. Three popular sizes exist, 0.96-inch, 1.25-inch and 2-inch barrel diameters. Almost every telescope you can imagine will accept eyepieces of one of these sizes, with the 1.25-inch size being by far the most widely used among manufacturers. To summarize some of the key points to consider when selecting an eyepiece:
Focal length — The eyepiece's focal length (usually in mm.) The larger the number, the lower the magnification it will provide.
Barrel diameter — Eyepieces come in 0.96-inch, 1.25-inch or 2-inch barrel sizes.
Magnification — The power the eyepiece provides with your telescope (this will vary depending upon the telescope.)
Apparent FOV — The apparent field of view in degrees. In general, eyepieces with a large apparent field will cost significantly more but provide an almost '3D-like' viewing experience, especially for deep sky observing of extended objects.
Eye Relief — Usually described in mm, this tells you how far your pupil must be from the rear element of the eyepiece to see the entire field of view. A longer eye relief gives a more enjoyable viewing experience, especially if you wear glasses.
Exit Pupil — The figure (also usually in mm) describes the size of the light cone at the eye relief position. Our dark-adapted pupil is never larger than 7mm, so any exit pupil size above this level is wasted light.
Best budget eyepieces
The Skywatcher Super Modified Achromatic eyepieces offer a small selection of 1.25-inch eyepieces at a remarkable budget price. While certainly not on the same level as more expensive designs, they provide surprisingly good views. The eyepieces also have nice rubber eye cups for comfortable viewing. They are ideal for the beginner or perhaps a budding young astronomer just starting out.
Best for range of choice
The Celestron Omni Plossl eyepiece range offers a nice entry-level range into the higher quality 4-element Plossl design. A wide range of focal lengths are available, all in 1.25-inch size aside from the 56mm eyepiece, which comes in a 2-inch size. These eyepieces produce sharp images, especially on axis and are well suited to planetary observations. Their narrow apparent field makes them usable for deep sky observation but not ideal.
Best wide-angle eyepieces
The Antares W70 Widefield range of eyepieces are perhaps some of the best available at this price point. Large clusters and nebulosities will easily fit into your field of view with high magnification. They offer very good quality with comfortable eye relief and wide apparent field making them well suited to deep sky observing. The only real negative I could find here is they don't appear to be as widely available as some other brands. That said, if you are looking for some good eyepieces on a budget these are well worth looking at.
Best for high power observing
The Celestron X-Cel LX eyepieces are a great, high-quality range of eyepieces for those interested in observing the planets. The focal lengths on offer are well suited to high-power observing, and the apparent FOV of 60 degrees is perfect for finding your way around the sky quickly. The image quality is sharp and well-corrected. The generous 16mm eye relief makes them ideal for spectacle wearers.
The bodies are made of stylish black-anodized aluminum with orange detailing, and the rubber tread around the middle improves grip.
Best for spectacle wearers
The Celestron Luminos eyepiece range represents the replacement for their popular Axiom (opens in new tab) eyepieces. These, however, are an improved high-end design but still lighter than the range they replace. They have twist-up eyecups and a parfocal eyepiece. This means little to no focusing is needed when changing from low to high power.
The comfortable eye relief and ultra-wide apparent FOV of 82 degrees make this a great choice for almost any kind of observing — from the moon and planets to galaxies and nebulae. Some sizes are only available in 2-inch size making them quite expensive.
Best for planetary observations
Takahashi is a well-known brand for producing optics of the very highest quality. Their Abbe Orthoscopic eyepiece range has become almost legendary among planetary observers, and these eyepieces are widely considered among the very best available for that purpose. A wide range of focal lengths are available to suit almost any telescope. Their narrow apparent field of view makes them unsuitable for deep sky observing.
Best for optical quality
Tele Vue is a brand that has become synonymous with top-quality optics since it was founded back in 1977. Their Plossl range of eyepieces is among the best available of its type offering top quality performance across the board. The Plossl range is perhaps best suited to high-power planetary observing due to their rather narrow apparent field of view. The contrast is sharp and clear all the way to the edge. A wide range of focal lengths are available to suit almost any telescope you'd wish to use them on.
Best for all round quality
While their Plossl eyepieces are undoubtedly superb, Tele Vue's Nagler series represent among the finest eyepieces available anywhere. They come in a range of focal lengths and are suitable for any kind of observing. The large 82 degree apparent field draws you in to the view, be it a rich star cluster or roaming across the rugged lunar landscape. Both 1.25-inch and 2-inch sizes are available. The price of these eyepieces means they are really targeted at more experienced observers.
Best bundle
Baader is a company well known for producing high-quality products. Their Hyperion eyepieces are highly regarded among amateur astronomers, and this full eyepiece set represents great value for money. Seven eyepieces are included ranging from 5mm to 24mm. These eyepieces also fit both 1.25-inch and 2-inch focusers due to their barrel design. These eyepieces also have very generous eye relief and large apparent FOV, making them well suited to any kind of observing.
Best overall
The Tele Vue Ethos range of eyepieces undoubtedly represents among the finest eyepieces available. Superb quality optics, generous 15mm eye relief and a vast 100-degree apparent FOV make for a captivating viewing experience. Using these eyepieces to view objects such as star clusters or bright nebulae is almost like floating in space. The view is also pin sharp and well corrected across the entire field. Alas, such quality does come at a price, but if you are looking for the very best available the Ethos range is well worth checking out.
How we test the best eyepieces
In order to guarantee you’re getting honest, up-to-date recommendations on the best eyepieces to buy here at Space.com we make sure to put every eyepiece through a rigorous review to fully test each instrument. Each eyepiece is reviewed based on a multitude of aspects, from its construction and design, to how well it functions as an optical instrument and its performance in the field.
Each eyepiece is carefully tested by either our expert staff or knowledgeable freelance contributors who know their subject areas in depth. This ensures fair reviewing is backed by personal, hands-on experience with each eyepiece and is judged based on its price point, class and destined use.
With complete editorial independence, Space.com are here to ensure you get the best buying advice on telescopes, whether you should purchase an instrument or not, making our buying guides and reviews reliable and transparent.