A telescope helps gaze through the stars in the universe and reveals distant cosmic objects and countless stars. It helps you understand the cosmos. An eyepiece is instrumental in providing eye comfort and acts as a bridge between your eyes and the telescope in your effort to explore the universe and locate objects.
The important aspects of the Telescope eyepiece are given below:
- Focal Length
- Optical Quality
- Barrel Size
- Apparent FOV
- Eye Relief
Reading and understanding the terms mentioned by each manufacturer will help you select the perfect eyepiece for your telescope. You will know about its compatibility with the chosen telescope model, which allows observing the objects with comfort. It also provides opportunities to explore more objects.
Measuring the AFOV of Eyepiece
You can measure the AFOV (apparent field of view) of an eyepiece in degrees. It helps you know how large the field of view is to your eye. An approximate field of view of a human eye is 150 degrees. An eyepiece with a larger AFOV, like 80 or 100 degrees, allows a more captivating sensation by covering a larger envelope.
You can imagine AFOV as a TV. A large-sized TV gives you a better and immersive experience. AFOV is different from ‘True Field of View (TFOV)’. The latter is the angular diameter of a piece of night sky under observation. It depends on the eyepiece’s AFOV and the magnification of your system.
Measurement of TFOV
You will have different TFOVs based on the combination of various eyepieces and telescope combinations. You can measure the TFOV in degrees and arcminutes. The angular size of the objects helps you identify what objects exist in the night sky. For instance, you need a TFOV of more than 0.5 degrees for a complete glance at the Moon.
Focal Length Determines What You Can Observe in the Night Sky?
Focal length determines what you can and cannot see in the night sky. It plays an essential role in selecting the eyepiece, like the GSO 20 mm Plossl Eyepiece for your telescope. It is crucial for the brightness of an image based on your ‘zoomed in’ view. You can enjoy higher magnifications with a low eyepiece. However, it yields dimmer images.
The GSO 20 mm Plossl Eyepiece is pocket-friendly and ideal for experienced and beginner astronomers. The 20 mm focal length is suitable for scanning ‘wide star fields’. It gives an apparent view of 52 degrees. It allows observing the Moon’s full disc or a large nebula. It improves brightness, clarity, and contrast with 4-element multicoated glass optics. It is one of the affordable eyepieces for telescope.
Importance of Selecting an Eyepiece with Good Quality Glass
A lower quality glass affects the viewing. Therefore, you can opt for an eyepiece with high-quality glass. High-quality optical elements ensure maximum light throughput and correct incoming light for high contrast and brighter views. The GSO 25 mm Plossl Eyepiece is pocket-friendly. Certain coatings protect the eyepieces from moisture, dirt, and scratches.
The GSO 25 mm Plossl Eyepiece offers better optical performance. It comes with an FMC (fully multicoated) lens design. It provides sharper images with high contrast and clarity. It is highly sought for observing larger objects in the deep sky and open star clusters. Its AFOV is 52 degrees.
Eye Relief is Vital for Comfortable Viewing of the Stars in the Night Sky
It refers to the safe distance you must maintain from an eyepiece for comfortable gazing at the stars in the night sky. Eye Relief is vital to observe the sky for longer durations. The GSO 15 mm Plossl Eyepiece offers an eye relief (of 13 mm). You can enjoy a comfortable viewing experience during astronomical observations.
Which one to choose: 2-inch or 1.25-inch-sized Barrel
The eyepiece’s barrel, which slides into a diagonal or the focuser, is available in sizes: 2” and 1.25”. You can select the right-sized barrel based on the diameter of the focuser and the required viewing experience. The barrels with a 1.25” size allow viewing brighter and smaller objects, such as planetary nebulae or the lunar craters, at high magnifications.
The GSO 6 mm Plossl Eyepiece boasts a barrel size of 1.25 inches. It is a standard for most telescope eyepieces. 1.25” barrel size is compatible with any telescope. It is economical compared to those with a 2-inch barrel. However, barrels with a size of 2” are expensive and offer a wider view and house larger lenses.
What Are The Types of Eyepieces?
There are three types of eyepieces, namely Zoom Eye Pieces, Wide Angle Eyepieces, and Plössls. Read on to know about the benefits and disadvantages. It helps you select the perfect eyepiece suited to your viewing experience.
Zoom Eyepieces
These eyepieces offer different magnifications with multiple focal lengths. They allow varying the magnification without the need for changing the eyepieces. They are suitable for terrestrial observing and outreach use with their range of magnifications. The eye relief and field of view decline as you move from high focal length to low focal length.
Wide Angle Eyepieces
Compared to standard eyepieces, these wide-angle eyepieces offer an immersive experience with their large field of view. Therefore, an eyepiece with an angle more than 80 degrees is called a wide-angle eyepiece. However, some models with an AFOV of 72 degrees and an angle of 68 degrees are also called wide-angle eyepieces.
Wide-angle eyepieces comprise 5 internal lenses to explore larger objects in deep space. It offers a captivating and more immersive experience for the stargazers. They are the most preferred eyepieces for deep space exploration.
What Are The Most Common Eyepieces?
Plössl eyepieces are designed with four lenses, keeping color fringing and chromatic aberration to a minimum. The four lenses are arranged in the 2 back-to-back ADs (achromatic doublets). They are ideal for gazing at the deep sky objects and planets.
The GSO 32 mm Plossl Eyepiece is economical and widely sought for its wide field performance, clarity, and value. It allows watching nebulae and open clusters in the night sky. It offers an eye relief of 22mm and an APOV of 52 degrees. They allow capturing contrast-rich and sharper images with minimal distortion.
How Do You Care for the Eyepieces?
You can keep the eyepieces safe and clean to improve durability. You can store them in screw top bolt cases. It protects the eyepieces from fingerprints, scratches, and dust. You can select soft or hard-sided cases as another layer of protection during travel.
You can utilize cleaning fluid to clean your eyepieces. It preserves the delicate coatings. Lint-free and soft brushes or clothes are ideal for cleaning the eyepieces without scratches on the glasses. You can also use a blower to remove dirt and dust from the Telescope eyepiece.
How DO You Calculate Exit Pupil and Magnification?
The Exit Pupil and Magnification depend on the focal length of your eyepieces. You will achieve a small Exit Pupil and higher magnification with a low focal length eyepiece. High focal length eyepieces yield a large exit pupil and lower magnification.
You can compute the Exit Pupil by dividing the Telescopic Aperture in mm by the magnification. You can also calculate the Exit Pupil by dividing the Eyepiece focal length by the Telescopic Focal ratio. You can calculate the magnification by dividing the Telescopic Focal Length by Eyepiece Focal Length.
Where Do You Buy Good Quality and Economical Eyepieces?
You can procure high-quality eyepieces at affordable rates from Modern Telescopes. It is India’s largest telescope store and engages in the sale of computerized telescopes, refractors, etc. It has established alliances with global leaders such as GSO, ZWO, Planewave, Unistellar, etc.
It offers faster shipping options for telescopic eyepieces and refractors. It also provides excellent warranty support. The customers can enjoy lifelong support for the products purchased at this store. Its mission is to ensure access to good-quality telescopes.
Conclusion
A telescopic eyepiece allows viewing distant objects in the sky comfortably and clearly. Selecting a perfect telescopic eyepiece is essential for better image quality. The quality of the eyepieces is vital for brighter and higher-contrast images.