Recommended Eyepieces & Accessories 2023
For anyone starting out in astronomy, understanding eyepieces is crucial. All visual telescopes need an eyepiece to function. Without it, you'd only see the telescope's mirrors or lens. A camera might work at the telescope's prime focus, replacing its lens, but our eyes aren't designed like cameras. We require an eyepiece, which is positioned within the telescope's focuser, to examine the image the telescope creates.
Categories of Eyepieces
There are several types of telescope eyepieces, each with its own unique design and characteristics. Here's a rundown of some of the most common eyepiece designs:
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Oldest design, primarily for low-power applications in refractor telescopes.
Typically has two lenses.
Not commonly used in modern telescopes due to its limited field
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Older design used mainly for terrestrial applications.
Also consists of two lenses.
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Three-lens design that offers improved color correction over Huygenian and Ramsden.
Good for lunar and planetary observation.
Middle-of-the-road in terms of cost.
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Four-lens design.
Known for its sharp, high-contrast views, especially good for planetary observing.
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Four-lens, symmetrical design.
Known for sharp images across a relatively wide field of view (often around 50°).
One of the most popular eyepiece designs.
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Five or six-lens design.
Offers wide fields of view, around 60° to 70°.
Good for deep-sky observing.
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A modern design known for extremely wide fields of view, up to 82° or more.
Provides almost "panoramic" views of the sky.
Often more expensive due to the complexity of the design
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Another design from Tele Vue (like Nagler) that offers even wider fields of view, up to 100°.
High-end, with premium performance and price.
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Three-lens design.
Known for high contrast and sharpness, but with a very narrow field of view.
Eyepiece Accessories
Eyepiece accessories enhance the capabilities of your telescope, enriching your stargazing experience. Whether it's optimizing visuals, improving comfort, or protecting your equipment, these accessories play a pivotal role in the world of astronomy. Here's a look at some of the most frequently used eyepiece accessories:
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An accessory that can double or triple the magnification of your eyepiece, extending the capabilities of your telescope.
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Particularly useful for refractor and catadioptric telescopes, they change the viewing angle for a more comfortable observation stance.
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These are attached to eyepieces to enhance specific celestial features. Common ones include lunar filters, light pollution filters, and nebula filters.
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These cases are vital for the safe storage and transport of eyepieces and other telescope accessories.
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Devices designed for aligning the optics of a telescope to ensure the best possible views. Especially vital for Newtonian reflectors.
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These tools enable the use of eyepieces with different sizes or can facilitate camera attachments for astrophotography.
Factors to Consider
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Focal Length (f)
Paramount in determining your telescope's magnification. This number, in millimeters (mm), is often printed on the eyepiece barrel.
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Eye Relief
This is the distance from your eye to where the full eyepiece view is visible.
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Apparent Field of View (AFOV)
This angle, measured from one eyepiece field side to the other, alongside magnification, determines how much sky is visible.
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Barrel Diameter
Typically either 1.25" (standard for modern eyepieces) or 0.965" (found in lower quality or vintage telescopes). Adapters are available for refractors with 0.965" focusers, allowing the use of the more standard 1.25" eyepieces.
Understanding Magnification
The magnification your eyepiece provides isn't fixed and varies based on your telescope. To select the right eyepieces, knowledge of your telescope's Aperture and Focal Length is necessary, generally found printed on the telescope.
Magnification: = Focal Length of Telescope / focal length of eyepiece.
Max Useful Magnification: = 2x Per mm of Aperture or 50x per Inch of Aperture.
Min Useful Magnification: = 3.6x per Inch of Aperture or 0.142x per millimeter of Aperture.
Focal Ratio: = Focal Length of Telescope / Aperture of Telescope.
Avoiding Common Pitfalls
Beware of cheap telescopes boasting absurdly high focal lengths, simply for marketing purposes. If magnification is prioritized over aperture in a telescope's advertisement, approach with caution. Over-magnifying leads to dim, blurred views with potential diffraction issues. Moreover, the atmosphere can hinder high magnifications. Atmospheric turbulence, or "bad seeing", can disrupt clarity. Typically, 200x is feasible; on exceptional nights, perhaps 400x. But if celestial bodies are low on the horizon, their images can be especially distorted.