My experience with accessories sold with a new telescope is that the eyepieces don’t cover all expectations. There are many quality eyepiece brands to choose to upgrade but knowing what to buy is a tad daunting.
Eyepieces are essential since they contribute to half of the optics in a refractor telescope vs. about a third in a reflector. Another name for eyepieces is oculars.
What are the best Telescope Eyepieces?
New telescopes often come with bottom-of-the-range type eyepieces. To upgrade and improve your views, choose a top-end brand like Tele Vue, which has quality-built designs, or you can settle for the best cheap telescope eyepieces of value and pick any Plössls.
Your telescope purchase price might’ve included a 9 mm and a 25 mm eyepiece, and sometimes a Barlow lens. While the 9 and 25 mm are basic workhorses and valuable, these inclusions are often low to mid-quality types. And, if you need to wear glasses while looking through the telescope, they probably won’t be satisfactory for comfort. Read on…
Best telescope eyepiece brand
Who makes the best telescope eyepieces? Tele Vue, with its Nagler, is considered the best telescope eyepiece brand on the market by many.
Some of Tele Vue’s most popular products include the Nagler eyepiece series, which features ultra-wide fields of view and exceptional image quality, and the Ethos eyepiece series, which offers even wider fields of view (100º) and unparalleled sharpness.
Tele Vue Nagler with 100º field of view
See it at Amazon
It’s a brand that’s been popular since the 1980s. Al Nagler, an amateur astronomer and optical designer, founded Tele Vue Optics in 1979 in New York, USA.
Tele Vue eyepieces (as sold at High Point Scientific) are built to last. They are designed with a rugged construction that can withstand years of use in the field. Tele Vue also offers a lifetime warranty on all of their eyepieces.
Quality eyepieces can improve any telescope’s performance.Terence Dickinson, Author, NightWatch: A Practical Guide To Viewing The Universe
Other popular brands of eyepieces for general observing of the night sky include:
The best eyepiece to get
For what to get, here are some recommendations from long-term users. Terence Dickinson, the author of numerous astronomy books, lists his favorite eyepieces as:
- Panoptics by Tele Vue
- Series 5000 Plössls by Meade
- Series 5000 Ultra Wides (Nagler type) by Meade
In forums, differing recommendations from amateur users, include:
- Gosky Plössl eyepieces
- Celestron X-Cel LX
- Celestron 93220
- Celestron 93432 Luminos
- Baader Hyperion
- Orion Lanthanum
- Orion 8728 Sirius Plössl eyepieces
- Some users also swear by GSO
Orion Telescopes is an online supplier where you’ll find some of these recommendations, such as the Orion Sirius Plossl…
Ideal for all types of telescopes, the 12.5mm Orion Sirius Plossl Eyepiece excels at vi… [More]
Best cheap telescope eyepieces
According to Dickinson, any Plössl is good value. I’ve used Plössl eyepieces and find they perform well. They’re good if you’re starting out or want the best budget telescope eyepiece to use in your hobby.
Gosky sells some of the best Plossl eyepieces at budget prices and often you can get their series at Amazon…
Gosky Plossl Telescope Eyepiece Set
Available at Amazon
telescope eyepiece Comparison
It can get confusing. You can get optical lenses with as many as eight elements.
How do they differ? Which is better? The following compares telescope eyepieces in order of the number of elements and expected quality from low to high plus the field of view range expected in each.
|Telescope lens type||Number of Elements||AFOV|
|Ultra wide-angle||multiple||up to 85º|
Some still prefer the orthoscopic telescope lens type for medium to high magnifications. These have a four-element design with a slightly wider FOV than earlier models.
These are cheap but fine for planetary viewing.
While Plössl lenses also have four elements they are considered superior to Orthos. They have a slightly wider FOV, are useful for low, medium, and high power, and are great for observing the planets and the moon.
They are a good budget buy.
Modern Wide-field telescope lenses
The wide-field modern design has 6 or 7 elements. With this much glass, we’re moving up towards the higher end of the market price-wise.
An example of wide-field optics is the Panoptic by Tele Vue (as seen at High Point Scientific) — one Dickinson recommends.
This is a premium buy with levels of performance Nagler-like.
The Nagler came on the market in 1981, introduced by Tele Vue. It’s regarded as the finest in the medium to high power category for giving sharp images.
Here we’re at the upper end of the scale, price-wise and quality-wise. The user experience has been described as “looking at the universe through a space-ship window”.
The Nagler design provides a wide field of view — check the Nagler eyepieces out at High Point Scientific.
Ultra wide-angle eyepieces for telescope
The Ultra Wide-Angle is a similar design of eyepiece to the Nagler and was introduced by Meade soon after Tele Vue brought in the Nagler — see it here at High Point Scientific.
Buyer’s Telescope Eyepiece Guide
The seven factors to check out when buying telescope eyepieces…
Barrel size that fits
The barrel size needs to fit your telescope focuser…
Take note of the barrel size on your telescope. This is the diameter of the eyepiece slot. It’ll likely be either 1.25″ or 2″. Make sure to shop for eyepieces matching that diameter or otherwise, you’ll have to buy an adapter.
There are 0.965-inch ones but this smaller diameter comes with cheap telescopes, which typically can only accommodate cheap telescope eyepieces with few elements (i.e. orthoscopic), small fields of view (about 30°), and poor eye relief.
Tip: Dobsonian reflectors and top-end apochromatic refractors generally use the larger 2-inch barrel size.
Price — Meets your budget
The price should match your budget without losing out on adequate quality.
As a guide: Dickinson estimates you should consider spending at least 1/3 of the cost of your telescope for the best telescope eyepiece kit.1
Note: Good quality eyepieces hold their value and can be used on subsequent telescope purchases. So, look at it as a long-term investment.
Adequate field of view
The field of view is the amount of sky seen through your telescope using your telescope eyepiece.
The field of view of the telescope eyepiece can range from 40° to 100°. The wider measure (100°) corresponds to a broader view of the sky. To better understand degrees with the field of view, see my article about measuring distances between celestial objects.
An eyepiece with a narrow FOV is on the other hand the best planetary eyepiece as it gives you a small bit of the sky in high magnification through the telescope’s view. However, expect to spend a bit of time fiddling to find and center your target object. For this purpose, a good finderscope helps.
Practical magnification Limits of your telescope
Pushing beyond the maximum practical magnification of your telescope will give you fuzzy images and the nightmare of trying to find and keep the object in view. In choosing a high-power eyepiece, keep this in mind.
As you know, the magnification of a telescope is determined by dividing the focal length of your telescope by that of the eyepiece used. For example, if the focal length of the telescope is 1000 mm and the focal length of the eyepiece is 10 mm, the magnification would be 100x.
Usually, manufacturers include the practical magnification limits in the telescope’s specifications. But you can estimate these yourself. For example, to obtain the maximum of these use either of these rule-of-thumb methods:
- Twice the telescope’s aperture in millimeters (mm)
So, if you have a 90mm aperture, then twice that, 180x, is the maximum useful magnification for that telescope.
- Multiply the aperture in inches by 50x
For a 4″ aperture, multiply it by 50 and you have 200x as the magnification to stay within.
But here’s the thing…
In practice, it could be as much as half these limits, e.g. under poor seeing conditions. And so, your useful magnification limit may fit better somewhere in these ranges shown in the table here.
|APERTURE SIZE||Multiply the aperture in inches by:|
|up to 5″||8–40|
So the ideal eyepieces for your kit will have focal lengths that provide magnification within your telescope’s practical magnification limits.
Exit pupil – the ideal
The exit pupil is the small, circular beam of light that is formed by the eyepiece of a telescope. It is the point where the light exits the eyepiece and enters the eye of the viewer.
The larger the exit pupil, the brighter the image you’ll see but there is a limit…
The ideal exit pupil for a telescope eyepiece varies with the viewer’s age.2 It is based on the mean pupil size of an adult in a dimly lit area. Having an exit pupil size that matches this allows the maximum amount of light to enter the eye.
On average, it’s around 7 mm for most adults of youthful age. As people age, their pupil size tends to shrink and for older users, 5 mm is likely.2
An eyepiece resulting in an exit pupil larger than your pupil size will mean light is being wasted but one that’s too small may not give you a bright enough image and may be impractical.
In choosing telescope eyepieces — you might want to consider the exit pupil for the shortest and longest focal lengths you choose for your telescope eyepiece kit.
To calculate the exit pupil, simply divide the aperture of your telescope by the magnification of the eyepiece. For example, if your telescope has an aperture of 150mm and a focal length of 1200mm and you’re using a 10mm eyepiece, the magnification would be 1200/10 = 120x, and the exit pupil would be 150/120 = 1.25mm.
A 4-mm eyepiece on the same telescope will have an exit pupil of 0.5 mm. Anything below 0.5mm can be problematic for image quality, e.g. seeing eye floaters etc.
Using the same specs as above, an eyepiece with a 40-mm focal length will give me an exit pupil of 5 mm and a 56-mm eyepiece will give me an exit pupil of 7. The longest focal length worth getting corresponds to an exit pupil size not exceeding your pupil size.
Exit pupil (ep) calculation #2:
A 10-mm focal length eyepiece in a 150-mm telescope with a focal length of 1200 mm yields an exit pupil of 1.25 mm. Estimated by…
EYEPIECE FOCAL LENGTH (MM) ÷ f ratio = EXIT PUPIL
i.e. 10÷(1200÷150) = 1.25 mm
where F ratio = Telescope Focal Length / Telescope Aperture
Lens coating that allows clear views
The options for eyepiece lens coating are untreated, multi-coated, or fully multi-coated. I compare these different coating types in my article on knowing your optical coatings. Magnesium fluoride (MgF2) is a common material in coatings.
Eypepiece lense coatings compared:
|Untreated||No coatings on any of the lenses. 10% light passing through is reflected.|
|Multi-coated||No coatings on any of the lenses. 10% of light passing through is reflected.|
|Fully multi-coated||All lens surfaces are treated with multiple layers of anti-reflective coatings. Much more light passes through.|
Look for eyepieces with coatings to reflect multiple bands of wavelengths that will show blue or purple reflections when held up to the light.
Eye relief is the maximum distance where you can position your eye away from the top eyepiece lens and still see the full field of view. This is especially important for wearers of glasses. I cover this in my article on eyewear with telescopes or binoculars.
Having your eye jammed up close to the lens with short eye relief, or worse, none, when using high power can cause discomfort. If you need to wear glasses, you might want to get a lens with a long eye relief, e.g. at least above 15 but possibly up to 18–20 mm.
Short eye reliefs are found in Plössls and orthoscopic types. They are generally around 12–15 mm.
Long eye-relief range: Also known as high eye relief, the following are known brands with a series providing comfort for eyeglass users:
- Tele Vue – Delos
- Vixen – LV series
- Celestron – Xcel
- Pentax – XW Series
How many eyepieces do I need for a good telescope eyepiece kit?
Having three eyepieces will give you a useful range of magnification — i.e. one in each category of power: low, medium, and high. Or… two eyepieces, a low- and a medium-power with a Barlow lens for a budget telescope eyepiece kit.
|POWER CATEGORY||Focal length|
Eyepieces usually have their focal length marked on the piece in mm along with the type of eyepiece. The thing to note — the smaller the eyepiece focal length (EFL) the higher the power.
A 2x Barlow lens will double the power of the eyepieces.
Imagine you have a 40 mm and an 18 mm eyepiece with a 2x Barlow lens. You’ll also get the equivalent of a 20 mm and a 9 mm eyepiece, respectively. This gives you a high-power option (9 mm) from a medium-power eyepiece (18 mm).
Is a Zoom eyepiece a good idea?
I’d probably steer away from Zoom eyepieces. Experienced amateur astronomers like Terrence Dickinson rate zoom eyepieces in the undesirable category. 1
Dickinson gives two reasons to steer away from these:
- Restricted field of view
- Tend to have inferior optical performance
- Nightwatch, a Practical Guide to Viewing the Universe by Terence Dickinson (available at Amazon). This book contains sky charts and has a spring binding so is practical for use on location.
- Jay C. Bradley, Karl C. Bentley, Aleem I. Mughal, Hari Bodhireddy, Sandra M. BrownJ “Dark-adapted pupil diameter as a function of age measured with the NeurOptics pupillometer”. Refract Surg. 2011 Mar; 27(3): 202–207. Published online 2010 May 17. doi: 10.3928/1081597X-20100511-01