What is the best Telescope for astronomy?
Given the broad range of telescopes available, as an enthusiastic, but inexperienced consumer, how would you choose the right telescope for your needs? The answer to this question will explain the different telescopes, but to understand more comprehensively, it is necessary to learn basics about telescopes for astronomy.
Aperture is the most essential factor.
The main feature for any telescope is the aperture. This term refers to the diameter of the primary optical element, which can be a mirror or a lens. The telescope aperture is related directly to two vital performance characteristics of the equipment: its ability to absorb light (determines how bright the objects will be displayed) and its resolution power (how detailed are the pictures). There are other details to consider when choosing a telescope, but you have to learn only one aspect, which is : the larger the aperture of a telescope (its width or diameter), the better, because more light enters the device.
Do not be fooled by magnifying power (600X, 1000X …).
Sadly, the first thing that comes to mind when a beginner wants to buy a telescope would be the magnifying capacity. A beginner should ask, “what is the diameter of the equipment?” Actually, any telescope can achieve any amplification, depending on the lens or mirrors used. The factor limiting the maximum effective magnification of any telescope is aperture, as you may have guessed. Increasing magnification, the image on the telescope is bigger, the light is projected on a larger area inside the telescope, and consequently, the image becomes darkened. There is an outright breaking point, dictated by the physical attributes of light, which determines the best image resolution for an aperture. To exceed the magnification limit, the image loses brightness and gradually turns into a bubble without resolution.
Magnification limit of any telescope is 50 times its aperture in inches or 2 times its aperture in millimeters. This corresponds to 100x or 120x for small telescopes, which are sufficient to observe the Saturn rings or Jupiter clouds. The 2x rule for each millimeter is simpler and may vary, more or less, depending on the optical quality of the gear and the observer vision. Experienced observers often use less power magnification; around 0.5x to 1x per millimeter is enough for most celestial bodies. Any manufacturer who states that a 60mm telescope can see well at 450x is passing the wrong information.
The bigger, the better, however…
While the aperture is the main aspect of a telescope, there are a few exceptions to this rule. The first is self-evident: portability. The largest telescopes are large and require a permanent home or observatory or enough muscles, a truck, and a strong back! There is a limit to performance and ease of movement. This limit exists, depending on physical and financial resources. Beginners should start with a Model with enough aperture and that is easy to maneuver. Avoid the temptation of the huge aperture. Those who cannot establish the limit, usually buy the biggest telescope on the market, without thinking of how to use it. These monster telescopes, usually, end up in a corner of the garage gathering dust, exiled for the crime of being too heavy and large, while the weekend enthusiast, instead of becoming star hunters, end up frustrated.
The sky is the limit
Another limitation of a telescope is less obvious, but it is clear after the first astronomy sessions: The Earth’s atmosphere sets a limit on how much you can observe. Planets and stars viewed on a telescope appear distorted as the light goes through the air. This is called “seeing” and becomes more apparent and hassling as the aperture increases. Mainly, it affects the observation of the Moon and planets, where more power is applied to expose more details, increasing the appearance of air turbulence.
The distortion, because of seeing, differs according to the air streams in the upper layers of the atmosphere, and less directly by the altitude and local topography. In a typical night and a regular local, turbulence can limit the magnification to around 250x or 300x, preventing telescopes bigger than 8 “or 10″ from reaching the most of their expansion performance. Telescopes bigger than 10” are commonly used by observers who prefer to view nebulas, star clusters, and galaxies in low light.
Last in sequence, but not least in importance to be covered, before entering the optical subject are the types of mounting. Telescopes can be found as Altitude and Azimuth (ALTAZ), moving up-down and left-right (altitude and azimuth), or equatorial alignment with Earth’s axis of rotation.
Azimuth mounts are usually easier to use and preferred if the telescope will be used for diurnal and astronomy observation. The top-quality azimuth mounts provide precision control with small increments and are recommended for magnifications up to 150x. Another variation of the Azimuth in called Dobsonian assembly. It uses unconventional materials, such as wood and Teflon, assembled in a way that moves easily, very stable, and able to support large telescopes at low cost.
For astronomical observation, the equatorial mounts are more suitable. Its advantage is facilitating the tracking of objects in the sky. This movement can be done through a precision manual control or by an electrical mechanism. The ease of viewing makes the equatorial mount a favorite for those who want to observe the planets and the moon. If you are keen to specialize in astronomical photography, the equatorial mount is the most recommended.
Different Telescopes for each type of observer
Now that we have learned the information about the basics of a telescope, its performance, and assembly, we can discuss three basic optical models: refractor, reflector, and catadioptric.
The refractor telescope is the model that most “stars hunters” think of when they hear the term telescope. It is a long, thin tube, assembled on a tripod with a lens on one side and an eyepiece on the other. This type of telescope was the first kind invented, and the most modern refractor models get the finest images for the aperture applied. They are usually chosen by watchers, who prefer the Moon and planets, by enabling sharper images and high contrast and high magnification, suffering less interference because of atmospheric features than other types of telescopes. They also are easier to maintain than the other types. Hence, they are preferred by beginner astronomers.
But, the quality and ease don’t come with a low price, and refractors are costly in value x aperture. Refractors can cost thousands of dollars and still are considered small for deep space observation. The long focal length limits the field of view, making it hard to see large objects as constellations and galaxies. And using a long tube and an eyepiece requires the use of a large and high tripod that, if it is not good quality, can lead an instability in the telescope, making it difficult to observe.
Orion ShorTube 80 Equatorial Celestron Omni XLT 150 Refractor Orion StarBlast 80mm AutoTracker Orion Grab-n-Go 80mm Triplet Refractor
The reflector telescope has mirrors, instead of lenses, to capture the light and focus it. The most common reflector would be Newtonian, which uses a concave primary mirror in the telescope bottom. A secondary mirror across directs light captured by a straight pipe eye. The Newtonian models offer the greatest possible apertures and when done well, can achieve excellent image quality.
Large reflector aperture greater than 10 ” Dobsonian assemblies are popular among astronomers, who are after the light buckets in deep space. These giant models have better performance during dark nights and away from large cities. The versatility and value of Newtonian models between 4.5 “to 8” with equatorial or Dobsonian mounts are an excellent choice for the beginner with broad interests.
The reflector Newtonian model demands occasional maintenance. As opposite the refractor, the mirrors need periodic alignment or collimation for better image sharpness. While many beginners face collimation as a complicated procedure, it is simple and doesn’t take more than a couple of minutes to do it. The tube on the reflector is open and exposed to air and moisture, unlike the refractor. If the mirrors are not protected by the tube cover, over time, it can gather dust and particles, requiring occasional cleaning. These are some of Reflector you can find on Amazon:
Celestron 127EQ PowerSeeker Orion SpaceProbe 130ST Orion 27194 XT8 Classic Dobsonian Meade LightBridge
The cutting edge of the three types of telescopes for amateurs would be the catadioptric, which combines mirrors and lenses to collect light and focus it. This model has the advantage of its compact size, since mirrors and lenses together can reduce the size of the tube and the aperture of the telescope without losing too much quality. Using an equatorial mount, this smaller telescope can be carried on more affordable mounts than required by a Newtonian. The catadioptric models are utilized by those who want a smaller size, without major loss of image quality and aperture.
The Schmidt-Cassegrain and Maksutov-Cassegrain names refer to particular catadioptric models that use different lens profiles for similar results. Maksutovs are usually associated with better picture quality, although there is little basis to prove this view. Probably, Maksutov has a reputation of a superior catadioptric, due the fact that spherical surfaces are less demanding to produce, compared with the high precision that Schmidt formats require. In high-quality recognized telescopes, both models achieve excellent image quality.
Some details are considered in catadioptric models. As with any telescope that uses mirrors, occasionally, it is necessary to make a collimation for better clarity. The price of a catadioptric is higher than a Newtonian of the same aperture, despite being cheaper than a refractor of the same aperture. More significant to astronomical observation, the second mirror in the catadioptric is bigger than the second on a Newtonian. Usually, astronomers who want high quality and ease of transport normally opt for catadioptric models. These are some of Catadioptric available on Amazon:
Celestron NexStar 6SE Celestron NexStar 130SLT Celestron Advanced VX 8in Meade 12-Inch LX200-ACF
Considering the price
Budget is a decision factor, in most cases. But three traps must be observed:
- Don’t buy a cheap model from the mall or supermarket with the plan to see how it works and to upgrade later. Most have low quality and often frustrate the beginner, so they give up the hobby or simply throw it away to buy a higher quality model.
- But, do not spend a fortune to start in astronomy. There are numerous excellent quality models with affordable prices that can show Saturn’s rings, the moon, and much more. Buying a good beginner model is the best way to decide how to invest in the future.
- Finally, if the price is not an important factor, think again before buying a gigantic model that usually are the dreams of many experienced astronomers. Usually, these models are difficult to handle and require an equally costly installation to take the best advantage.
Before reaching any conclusion, here is advice for beginners who want to jump in astrophotography, “NO!” At least, until you gather enough skills about how to operate your telescope and where the objects are in the sky. Paradise Photography can be an excellent activity to spend your time, but is a combination of science and art with a huge learning curve that discourages beginners who try to do everything at once. Astrophotography is the number one interest, and there isn’t anything wrong when selecting a telescope, based on the ease of adaptation of a camera in the near future. While most telescopes can be used for amateur photographs, the most important aspect of an astronomical photography instrument is the equatorial mount and the ease of connecting a camera that can focus. For a series of economic and technical reasons catadioptric telescopes with 8″ aperture are most commonly used for astronomical photography. They also serve as excellent equipment for observation .
So what is the best telescope? This decision must be taken individually, but there are two tips below:
- The best telescope is one you can use more regularly. A huge and excellent telescope with flawless optics is not useful in the garage or closet.
- Considering that all are equal, a telescope with greater aperture has better results than smaller aperture
My last advice will be to pick a well-designed telescope, which fits as best as you can to your observing passion and most frequent finding site. Make certain it’s a size you can manage easily (by your standards and nobody else) and can be used frequently. If you do all these things, then you ought to appreciate a lifetime of fulfilled watching!
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