Celestron NexStar Telescopes
Celestron telescopes have dominated the market for a long time, competing for the limelight with brands like Meade and SkyWatcher. Recently, Celestron celebrated 50 years of making advanced telescopes, having pioneered its first telescope in the early 1960s. When Tom Johnson developed the Celestron brand, he had a vision to introduce high-tech, low-priced telescopes.
The first Celestron was an improvement of the earlier Schmidt-Cassegrain design. Johnson was to manufacture an ultra-precise corrector plate which paved the way for future Schmidt-Cassegrain telescopes (SCTs). Before this breakthrough, it was difficult and expensive to design Schmidt corrector plates.
Although the first Celestron was a Schmidt-Cassegrain design, it was non-computerized. Computerized SCTs came later in the late 1980s. By the 1990s, Celestron was marketing computerized telescopes with the Schmidt corrector glass and on two occasions during the 90s decade, NASA used the C5 and C8 in their orbit tours.
What is a Schmidt–Cassegrain telescope?
Schmidt-Cassegrain telescopes (SCTs) are very popular among amateur astronomers and this popularity has skyrocketed in the last two decades.
A Schmidt-Cassegrain telescope is a type of catadioptric design telescope. Catadioptrics (CATs) use a combination of lenses and spherical mirrors to map celestial objects. Another feature of SCTs is the curvature-shaped corrector plate placed on the front side of the secondary mirror. This corrector plate is a real lens that alleviates spherical aberrations.
Why are Schmidt–Cassegrain telescopes so popular?
There are a few reasons that make SCTs popular among amateur astronomers. One, they are affordable. Two, SCTs are easy and comfortable to operate. Third, they are versatile.
Catadioptrics are simple to operate. An SCT is one of the most-comfortable telescopes you can own as it is straightforward to track objects as they transit the night sky for long periods. All this thanks to built-in motor systems.
SCTs are versatile in the sense that you are not limited in what you can do. They are also great at exploring our solar system and observing lunar details. Refractors tend to shine here but you could explore comets, asteroids, and the planets with an SCT.
Also, SCTs are quite straightforward when it comes to capturing Astro-images. When combined with CCD cameras, CATs can deliver pleasant astrophotos and even uncover some hidden gems! You can begin capturing DSO images on your first use of an SCT without having to do any complicated modifications just by pressing a few buttons!
In addition, SCTs often have a large aperture. Comparing a 6-inch refractor with an 8-inch SCT; the SCT has almost twice as much light gathering capability.
|Ideal choice for amateur astronomers|
Easy and comfortable to use
Can be lightweight and compact
Wide field of view
Long focal length
Razor sharp optics.
Excel in entry-level astrophotography
Perfect for deep sky, lunar, and planetary observing
Integrated with “Go-to” computer capabilities
Less expensive compared to refractors of equal aperture
Compatible with camera adapters
Many available accessories
Durable and need less maintenance
Optical tubes ranging between 6” and 14” are compatible with Fastar Technology
|As the focal length increases, portability decreases|
Compared to refractors and Newtonians, SCTs have a small field of view due to longer focal length
Shifting of the image due to gradual movements of the mirrors
During cold nights, corrector plates can collect dew
Lack of detailed contrast because of the enlarged diameter in the secondary mirror
For advanced astrophotography, requires extra accessories
Optics performance suffers when combined with full-size DSLR or CMOS sensors
Assembling and disassembling can take a considerable time
Noticeable coma and field curvature when imaging with large sensors
What is a computerized telescope?
The era of computerized telescopes kicked off towards the end of the 20th century. This was a mega revolution in the astronomy landscape. As computer-controlled telescopes evolved, more aspirants became more keen with astronomy. Today, it is not a surprise to find low-priced, entry-level computerized telescopes.
When tracking objects, the technique you follow will depend on the type of mount attached. Computerized mounts have driving motors that guide the entire scope to find and track celestial objects within its field of view. The slewing speed can vary, ranging between 6 and 24 degrees per second.
Computerized telescopes improve the pointing and tracking precision of celestial objects. The setup can be a single-fork mount or a dual-fork mount with built-in driving motors. Integrated into the mount is a handheld control device with an intuitive keypad. The mount used can be an Alt-azimuth or an Equatorial Mount system.
Computerized mounts are convenient to use as they remove the need for manual tracking. “GoTo telescopes” is the collective name for computer-controlled telescopes.
A computerized telescope gives you ample time to view and image target objects, unlike manual tracking where you spend more time following subjects. Also, because GoTo mounts polar align with the axis of the earth, observers can follow a trail of stars in the night sky with ease. This aspect extremely advantageous for long exposure astrophotographers.
As the earth rotates, a telescope observer gets the impression of a moving night sky. Thus, positioning the telescope to stay on target as the objects appear to move can be a real challenge. A manual telescope can miss a passing object, especially at high magnification. Usually, this is not the case with planets, the moon, and star clusters (galaxies) though. In long-exposure astrophotography, even a slight movement of the object can bring out a blurry image.
The main components of a computerized telescope:
- A computer system. The computer matches both The Reclination Axis (RA) and Declination Axis (DEC) of the celestial sphere with the coordinates of the telescope’s mount. This computer system features a firmware programmed with a database of stars and deep-sky objects. Also, it features the coordinates of the moon and planets.
- Motors. The motors enable the telescope to point at diverse objects (slewing), as well as track the target objects. Motors operate at a different range of speeds. You can expect some backlash at various speeds. Some telescopes can compensate for this delayed slewing.
- Encoders. Encoders are rotational sensors that pick up any movement the telescope makes and relays this information to the computer system. These sensors only measure the relative motion.
How a computerized telescope works
Computerized telescopes feature dual-speed motors fitted on both altitude and azimuth axes. The motors then connect to the on-board computer system, a built-in control device that resembles a TV remote, known as a “Hand Controller”. Pressing a button on this hand controller spins the dual motors which points the telescope towards your desired target, tracking its movement. If you are keen on observing objects rather than spending enormous time looking for the objects, computerized telescopes are the way to go. In contrast, telescopes without GOTO technology capability can be a real challenge to use since tracking is done manually.
Some GOTO telescopes have a built-in GPS system. A GPS enabled telescope has an advantage over a non-GPS telescope by knowing where you are and the positions of objects in the sky relative to your position. This makes finding objects and tracking to be easy as pie.
|Extremely simple to find and track celestial objects;|
Capturing DSO images can be automated;
Suitable for deep sky observers;
Complement well with CCD imaging cameras;
Integration with advanced, unique technologies;
No need to use charts;
Work even in low visibility;
|Non-tech savvy people may find the process complicated;|
Set up requires that you polar align the telescope with one or two stars;
Non-GPS computerized telescopes require that you enter data such as data, time and location manually each time you use them;
Why should you get a Celestron NexStar telescope?
Over the years, Celestron has released a range of telescopes, varying from SCTs, Newtonian reflectors, Cassegrains to refractors. Let’s discuss why the Celestron Nexstar telescope series is an excellent choice for you.
With 50+ years in the telescope manufacturing business, Celestron has established an excellent reputation. Although Celestron competes with other brands, Celestron has contested to stay ahead. They have devoted many years of research and resources into developing advanced telescopes with premium build-quality, while still being affordable for amateur astronomers.
The major selling point for Celestron telescopes is the Schmidt corrector plate integrated with their SCT models. Because Celestron follows a unique design process, the company can create uniform corrector plates at a low cost. Celestron telescopes exude a robust build quality matched with the stylish, attention-grabbing finish, plus their telescopes are ergonomically designed. You will not strain during observing, an inherent feature with many SCT telescopes.
Lastly, the optical tubes come coated in a different finish, from Blue, Orange, to Gray.
Exploring the sky with a programmed telescope is so much fun no matter if you are exploring close at home, faint galaxies or star clusters in the deep sky. Celestron telescopes include various technologies to automate slewing and tracking of objects which makes observing the night sky a breeze.
SkyAlign alignment procedure is one of their patented technologies. SkyAlign technology enhances accuracy and speed when slewing and tracking. You can set up your telescope and start to observe within minutes even if you have no prior knowledge of the sky. You only need to point your NexStar at two or three bright stars and it will do the rest. Your NexStar can locate and track any celestial object in its catalogue of over 40,000 celestial objects. Also, you get extra alignment procedures like Solar System Align and 3-Star Align.
If you wish to buy a telescope for astrophotography and capture sharp Astro-images, you can take advantage of the Fastar technology. You can attach a CCD or DSLR camera in place of the secondary mirror to get a wider field of view images at fast focal ratios (f/2). This makes their line of NexStars great for astrophotography.
One reason SCTs are popular is that they offer a large aperture over a short optical tube length. Although their size can be bulky, when you include telescope parts, they can easily be moved.
You can dismantle your Celestron Nexstar telescope into lightweight, movable parts. For the bulky telescopes like the 8-inch SCT, the optical tube and fork mount are detachable. Thus, you can move the telescope in two or three large boxes.
Usually, your Celestron telescope will weigh as light as 30 pounds and 50 pounds. Some bulky types can be more than 100 pounds. As for the length of the optical tube, the size varies between 16 inches and 30 inches.
Celestron Nexstar telescopes render clear, sharp views or images. This family of telescopes is among the most versatile with a focal ratio ranging between f/4 and f/14. Generally, most of the telescopes from this brand feature medium focal length – f/8 and f/10. This focal ratio is ideal for both visual observing and casual astrophotography.
A Nexstar SCT paired with a focal ratio of about f/10 shines in planetary and lunar observations. Galaxies like the M51 and the Whirlpool Galaxy are visible with an 8-inch SCT, although the spiral patterns are well defined with a 5-inch CAT. A 5-inch or 8-inch SCT will reveal Nebulas like the Great Orion Nebula (M42) and the Ring Nebula (M57). That’s not all: globular clusters like the Great Cluster in Hercules (M13) have a remarkable resolution with the C8.
Lastly, Celestron telescopes use advanced StarBright XLT optical coatings. These multi-layer and anti-reflective mirror coatings enhance light transmission, rendering brighter, sharper views.
WIFI and GPS functionalities
Some of the NexStar telescopes have WIFI functionality. Thus, you can control your Celestron Nexstar with a tablet or Smartphone using the SkyPortal App. Some models like the NexStar 8i are integrated with GPS functionality.
Your Celestron telescope will come with various accessories like a tripod, accessory tray, dew shield, diagonal, eyepiece kit, flashlight, star pointer Finderscope, an Aluminum carrying case and Barlow lenses.
Some examples of Celestron Nexstar telescopes
- Price: $$$
- Optical tube size: 22 inches.
- Telescope weight: 61 lbs.
- Mount: Dual-fork GOTO Alt-azimuth.
- Price: $$
- Optical tube size: 17 inches
- Telescope weight: 33 pounds.
- Mount: Single-fork computerized/motorized alt-azimuth.
- Pricing: $$
- Optical tube size: 22 inches.
- Telescope weight: 46.6 lbs.
- Mount: single-fork Computerized/motorized alt-azimuth.
- Price: $$
- Optical tube size: 17 inches.
- Telescope weight: 74 pounds.
- Mount: motorized/computerized alt-azimuth (dual fork).
- Price: $
- Optical tube size: 16 inches.
- Telescope Weight: 21 lbs.
- Mount: single-fork computerized alt-azimuth.