When buying a telescope, especially your first one, make sure not to rush the selection process. It would help if you didn’t run to the closest department store to acquire your first instrument. Pay no attention to eye-catching stickers promising high magnification power and other marketing tricks. Find a trusted store that sells quality optical equipment in your area. Instead of so-not-helpful advertising slogans, you will get professional help and advice, not to mention a proper quality instrument that will serve you for years.
Magnification power depends on how much light a telescope can gather. And the light-gathering power of a telescope depends on the size of its objective lens or mirror (aperture). The valuable magnification power of a telescope (if you observe in clear skies using a quality instrument) equals double the telescope’s aperture in millimeters (or about 50x per inch of aperture).
Sometimes you can see inexpensive 50-millimeter refracting telescopes that claim to be capable of providing 500x magnification power. Technically that is possible, but, considering the preceding, you can certainly tell that the optics of such an instrument only produce a 100x increase.
What telescope to choose?
Such a question cannot be unambiguously answered; it depends on your preferences and goals. Are you going to observe in a visual mode, or do you want to take pictures and record videos? How much money are you willing to spend? It is impossible to give a straight answer to all people at once.
The optical equipment market offers various telescopes in different price categories. Once you decide your price limit and your goals and needs, everything will become much more apparent. Even better is testing the desired telescope model before buying it (for example, at particular amateur astronomer’s gatherings or other astronomy events).
To make the right choice, carefully read all the information about your potential future telescope: product descriptions, specifications, and manuals. The convenient catalog will help you find exactly what you are looking for. You can find suitable models according to your experience level, telescope optical design, observed objects, etc.
What should I know about the optics?
A telescope’s most important attribute is its aperture (the diameter of the objective lens or mirror). The bigger the objective lens, the more light you will gather. Large aperture telescopes allow you to observe fainter celestial objects and get more detailed views. Yes, it is that simple – large telescopes will give you clearer, sharper views because they are more extensive.
The aperture of a telescope is always specified in the product description, and look for the “objective lens/mirror diameter” or “aperture.” As one of the most essential features of a telescope, it is often referred to in the title. For example, Levenhuk Skyline 70×700 AZ Telescope: 70 is the telescope’s aperture in millimeters; 700 is its focal length in millimeters.
How to determine the efficiency of optics?
There are a few essential details here.
First of all, poor assembly may affect the telescope’s efficiency. Fortunately, amateur optical instruments are relatively easy to manufacture, and most work fine.
Secondly, different optical designs perform differently.
Schmidt-Cassegrain and Maksutov-Cassegrain telescopes
Newtonian telescopes and Refractor telescopes
All these telescope types have strong and weak points. However, these differences are relatively small. The same aperture telescopes of different optical designs will have almost identical efficiency, and apparent differences become noticeable only when the aperture increases by 10-20%.
Atmospheric turbulence limits the telescope’s ability to transmit fine details of the image, and the background glow of the sky limits the telescope’s ability to detect faint celestial objects. Atmospheric turbulence is more harmful for large telescopes than small ones. So if you have to observe such conditions most of the time, buying a large instrument needs to make more sense.
However, large aperture telescopes will show you a more significant number of faint objects, even if you observe in bright skies. Many amateur astronomers scout out the area to find places with a peaceful atmosphere and go there occasionally to see what their instruments are capable of.
However, the aperture is the main thing. The world’s best 90mm fluorite apochromat cannot compete with a 150-mm homemade Newtonian reflector – that’s simply the law of physics!
How to develop my observing skills?
Even experienced observers believe that observing skills come to you intuitively, that all you need to do is “keep your eyes open” and practice more. But generally, that is not the case. To become an objective professional observer, you must practice, constantly learn and try something new. Purchasing a large telescope to see more is the same as buying a large pan to cook better. It is correct, but, as you know, cooking depends mostly on knowledge and experience rather than on applied tools. The same applies to astronomical observations.
Practice is free and more effective than a race for new instruments. An experienced observer with a mediocre device can see much more than a beginner with an excellent powerful telescope model. So what qualities do you need to develop to become a better observer?
First of all
Patience. Looking for celestial objects in the sky might take much time, even if you know their exact location.
Perseverance – your eyes, telescope, and skies do not remain constant from night to night.
Dark adaptation – it is essential to avoid bright light before observations; it might take hours before you reach your maximum seeing capacity.
Peripheral vision – the central part of the retina gives a clear color image, but the peripheral region is much more sensitive to light. You can see very faint objects and their low-contrast parts using your peripheral vision.
Moreover, several helpful observation tricks will help you see even more.
Eliminate the scattered light, distracting the eye from faint objects. To do so, use eyecups or special capes (if you do not have special tools, use some of your clothes) to cover your head while observing.
Move the telescope – our eyes respond to movement and sometimes “exhibit” faint objects that were invisible before. Try it with your peripheral vision.
Do not move the telescope – our eyes can store photons for seconds and show the weak parts. Try it with your peripheral vision.
What should a beginning amateur astronomer do first of all?
For a start, you should never forget to listen to good advice. Books can only replace first-hand experience. Join a local astronomy club, attend astronomy events with actual observations, and try looking through different telescopes. You will gather helpful information and meet exciting people who like sharing their thoughts and experiences on observing techniques and optical equipment.
You can find astronomy clubs and societies by visiting planetariums and science and technology museums and contacting physics departments at nearby universities. Also, you can find addresses in amateur astronomy magazines and, of course, on the Internet.
Answer the following five questions.
When choosing a telescope, especially for the first time, one can be slightly astonished by the broadest range of available models. To make the right choice, answer the following questions.
How much effort are you ready to put into studying the sky?
Suppose you know the constellations and can orient in the sky using the star hopping method and star charts. In that case, you can successfully use a telescope, which is less expensive, smaller, and lighter than a telescope with a computer-controlled mount.
How much effort are you ready to put into mastering your observing skills?
The ability to see details in celestial objects as well as the ability to see faint objects require a lot of practice and special knowledge. But it’s gratifying – under the same atmospheric conditions, an experienced observer can notice details that a novice can miss even observing through a more powerful telescope.
How far are you able and willing to transport your telescope from its storage place to an observational spot?
The differences in telescopes’ optical designs and hence their sizes lead to a significant difference in portability. And, of course, it’s better to have an easily portable, lightweight telescope that can be frequently used for its intended purpose than a bulky instrument whose only purpose is to take up space and collect dust because it’s too large or too heavy.
Some astronomers enjoy various technological novelties as they are isolated from their real practical value and economic justification of their cost.
Are you ready to spend money on sophisticated equipment, even if there is no particular need for it?
If yes, it might suit your skills since high-tech equipment sometimes incentivizes self-improvement. Some equipment is also considered a sign of good taste in amateur astronomy. Suppose the answer is no; think twice before buying a new astronomy-related product. Do you need it? Don’t let hype advertising affect your buying choice.
Do you want to take pictures or CCD images of celestial bodies?
Astrophotography is a costly hobby. And it’s not only about the money. Generally, it takes several years and several sets of equipment to get fully satisfying results. So astrophotography is a lot more costly and time-consuming than visual observations.
What can you see through a telescope?
The best way to find out is to look through a telescope in the company of an experienced amateur astronomer from your local astronomy club.
In general, you will be able to see all planets as disks. You will witness cloud bands and the Great Red Spot on Jupiter and Saturn’s rings. You will see its polar caps when Mars is near the closest approach to Earth. Mercury and Venus will show you their phases but nothing more. You will see four moons of Jupiter and Saturn’s moon Titan as dots; relatively bright comets will also become visible.
You should not expect to see images as large, bright, and detailed as the ones produced by the Hubble telescope.
Why would anyone spend billions of dollars on creating a space telescope if it were possible to see the same with a $100 amateur telescope?
As for deep-sky objects, most modern telescopes can show you almost all objects from the Messier catalog. At first, galaxies will appear to you just as weak spots. But if you look closely, you can see its spiral structure. The observed image will still be far from the astrophotography images you can see on the Internet. Remember, most galaxies are millions of lightyears away from us. Don’t expect images to have bright colors – most objects are just too weak for a human eye to register their color.
Can binoculars be an alternative to a telescope?
Hundreds of deep-sky objects are large and bright enough to look good through a 50-mm objective lens under low magnification. Medium-sized binoculars like 7×50 and 10×50 (where 7 and 10 are magnifications and 50 is the aperture) are reasonable for beginners.
Such binoculars are affordable, portable, and easy to use. But to be able to use astronomy binoculars with success, first, you need to study the starry sky in detail and also make sure that the binoculars are light enough, so you can hold them without tiring and the image shaking.
What to read for a beginner astronomer?
Some of the best books for getting familiar with constellations and celestial objects are “Discover the Stars” by Richard Berry, “Patterns in the Sky: An Introduction to Stargazing” by Ken Hewitt-White, and the more practice-oriented “Astronomy: A Step-by-Step Guide to the Night Sky” by Storm Dunlop. Most amateur astronomers had started their astronomical journey with these beautiful books. Besides that, you can use any amateur astronomer handbook to learn the basics.
We also would like to recommend some additional engaging astronomy titles: “Astronomy” by Ian Ridpath, “The Backyard Astronomer’s Guide” by Terence Dickinson and Alan Dyer, “Astronomy Demystified” by Stan Gibilisco, and “Illustrated Dictionary of Practical Astronomy” by C. R. Kitchin.
