Sky-Watcher 20mm Ultra-Wide Angle 66° 1.25" Eyepiece

Description

Sky-Watcher 20mm Ultra-Wide Angle 66° 1.25" Eyepiece

The Sky-Watcher 20mm Ultra-Wide Angle 66° 1.25" Eyepiece is a versatile wide-field eyepiece designed for comfortable low-to-medium-power observation. With its 20mm focal length, 66° apparent field of view, and standard 1.25-inch barrel, it is well suited to general observing, sweeping star fields, viewing open clusters, and exploring many bright deep-sky objects.

Wide-Field Viewing with a 20mm Focal Length

The 20mm focal length provides relatively low magnification in many telescopes, making it useful for locating objects and enjoying broader views of the night sky. It is especially suitable for observing extended targets and star-rich regions where a wider field of view is desirable.

The actual magnification depends on the focal length of the telescope. For example:

• A 600mm focal-length telescope provides 30× magnification.
• A 750mm telescope provides approximately 38× magnification.
• A 1000mm telescope provides 50× magnification.
• A 1200mm telescope provides 60× magnification.

This makes the 20mm eyepiece a practical choice for general-purpose observing and for use before switching to shorter focal-length eyepieces for higher magnification.

66° Apparent Field of View

A key feature of this eyepiece is its 66° apparent field of view. Compared with narrower standard eyepieces, the wider apparent field provides a more open and immersive viewing experience.

The extra field is particularly useful when observing star clusters, nebulae, large lunar regions, and dense areas of the Milky Way. It can also make manual tracking easier because objects remain within the visible field for a longer period before drifting out due to Earth's rotation.

The actual true field of view depends on the telescope and its focal length.

Multi-Coated Optics

The Sky-Watcher 20mm Ultra-Wide Angle Eyepiece features multi-coated optics designed to improve light transmission and reduce unwanted internal reflections.

These coatings help support bright, clear views with good contrast, which is useful when observing both bright objects such as the Moon and fainter targets such as star clusters and nebulae.

Final image quality will also depend on the telescope's optics, atmospheric conditions, focusing accuracy, and observing environment.

Comfortable 18mm Eye Relief

With approximately 18mm of eye relief, the 20mm model offers comfortable viewing for many observers. The longer eye relief allows the eye to remain at a practical distance from the eyepiece while still providing access to the wide apparent field.

A rubber eyecup helps guide eye placement and improves comfort during longer observing sessions.

Suitable for Deep-Sky and General Observation

The 20mm focal length makes this eyepiece particularly useful for a wide variety of observing targets, including:

• Open star clusters
• Bright nebulae
• Galaxies
• Large lunar regions
• Double stars
• Star fields and Milky Way regions
• General sky scanning

It can also be used for planetary observation, especially in telescopes with longer focal lengths, although shorter focal-length eyepieces are generally preferred when higher planetary magnification is required.

Useful as a Finder Eyepiece

Because it provides lower magnification and a relatively wide field, the 20mm eyepiece can also serve as a useful finder eyepiece. It can help the observer locate and center an object before changing to a shorter focal-length eyepiece for closer examination.

This can be especially helpful when using a manually operated telescope.

Standard 1.25" Barrel

The eyepiece uses a standard 1.25-inch barrel, making it compatible with a wide range of telescopes, diagonals, and focusers that accept 1.25" eyepieces.

Its compact size also makes it convenient to carry as part of a general astronomy eyepiece set.

A Versatile Wide-Field Eyepiece

The Sky-Watcher 20mm Ultra-Wide Angle 66° 1.25" Eyepiece combines a useful 20mm focal length with a wide 66° apparent field of view, multi-coated optics, and comfortable 18mm eye relief.

It is a practical choice for observers looking for a general-purpose eyepiece for wide-field exploration, deep-sky observation, lunar viewing, and object locating. Used together with shorter focal-length eyepieces, it can form part of a flexible eyepiece collection covering a wide range of magnifications.

Specifications

Please note:  The actual product may differ slightly from the images in color, finish, or other minor details.