In this section we tried to put together the fragmentary information that can be found on the Internet. There is a lot of information, but it is not systematized and scattered. We, guided by many years of experience, have systematized our knowledge in order to simplify the choice for novice astronomy lovers.
Main characteristics of telescopes:
Typically, the name of a telescope indicates its focal length, lens diameter, and mount type.
For example, Sky-Watcher BK 707AZ2, where the lens diameter is 70 mm, the focal length is 700 mm, the mount is azimuth, second generation.
However, the focal length is often not indicated on the telescope labeling.
For example Celestron AstroMaster 130 EQ.
A telescope is a more versatile optical instrument than a spotting scope. A larger range of magnifications is available to him. The maximum available magnification is determined by the focal length (the longer the focal length, the greater the magnification).
To display a clear and detailed image at high magnification, the telescope must have a large diameter lens (aperture). The bigger, the better. A large lens increases the telescope's aperture and allows you to view distant objects of low luminosity. But as the diameter of the lens increases, the dimensions of the telescope also increase, so it is important to understand under what conditions and for observing what objects you want to use it.
How to calculate the magnification of a telescope?
Changing the magnification in a telescope is achieved by using eyepieces with different focal lengths. To calculate the magnification, you need to divide the focal length of the telescope by the focal length of the eyepiece (for example, the Sky-Watcher BK 707AZ2 telescope with a 10 mm eyepiece will give a magnification of 70x).
The multiplicity cannot be increased indefinitely. As soon as the magnification exceeds the resolving power of the telescope (lens diameter x1.4), the image becomes dark and blurry. For example, a Celestron Powerseeker 60 AZ telescope with a focal length of 700 mm does not make sense to use with a 4 mm eyepiece, because in this case it will give a magnification of 175x, which is significantly greater than 1.4 times the diameter of the telescope - 84).
Common mistakes when choosing a telescope
- The higher the multiplicity, the better
This is far from true and depends on how and under what conditions the telescope will be used, as well as on its aperture (lens diameter).
If you are a beginner astronomer, you should not chase high magnification. Observing remote objects requires high degree training, knowledge and skills in astronomy. Moon and planets solar system can be observed at magnifications from 20 to 100x. - Buying a reflector or large refractor for observations from a balcony or from a city apartment window
Reflectors (mirror telescopes) are very sensitive to atmospheric fluctuations and to extraneous light sources, so it is extremely impractical to use them in urban conditions. Large aperture refractors (lens telescopes) always have a very long tube (for example, with an aperture of 90 mm, the length of the tube will exceed 1 meter), so their use in city apartments is not possible. - Buying a telescope with an equatorial mount as your first
The equatorial mount is quite difficult to master and requires some training and qualifications. If you are a beginner astronomer, we would recommend purchasing a telescope on an alt-azimuth mount or a Dobsonian mount. - Buying cheap eyepieces for serious telescopes and vice versa
The quality of the resulting image is determined by the quality of all optical elements. Installing a cheap eyepiece made from budget optical glass will negatively affect image quality. Conversely, installing a professional eyepiece on an inexpensive device will not lead to the desired result.
FAQ
- I want a telescope. Which one should I buy?
A telescope is not something you can buy without any purpose. A lot depends on what you plan to do with it. Telescope capabilities: show both terrestrial objects and the Moon, as well as galaxies hundreds of light years away (only the light from them takes years to reach the Earth). The optical design of the telescope also depends on this. Therefore, you must first decide on an acceptable price and object of observation. - I want to buy a telescope for my child. Which one should I buy?
Many manufacturers have introduced children's telescopes into their range especially for children. This is not a toy, but a full-fledged telescope, usually a long-focus achromatic refractor on an azimuthal mount: it is easy to install and configure, it will show the Moon and planets well. Such telescopes are not very powerful, but they are inexpensive, and there is always time to buy a more serious telescope for a child. If, of course, the child is interested in astronomy. - I want to look at the moon.
You will need a telescope “for near space.” In terms of optical design, long-focus refractors, as well as long-focus reflectors and mirror-lens telescopes, are best suited. Choose a telescope of these types to suit your taste, based on price and other parameters you need. By the way, through such telescopes it will be possible to look not only at the Moon, but also at the planets of the Solar System. - I want to look at distant space: nebulae, stars.
Any refractors, short-focus reflectors and mirror-lens telescopes are suitable for these purposes. Choose according to your taste. And some types of telescopes are equally well suited for both near space and far space: these are long-focus refractors and mirror-lens telescopes. - I want a telescope that can do everything.
We recommend reflex lens telescopes. They are good for ground-based observations, for the Solar System, and for deep space. Many of these telescopes have simpler mounts and computer guidance, and are a great option for beginners. But such telescopes have a higher price than lens or mirror models. If price is a factor, you might want to look at a long-focus refractor. For beginners, it is better to choose an alt-azimuth mount: it is easier to use. - What is a refractor and reflector? Which is better?
Telescopes of various optical designs will help you visually get closer to the stars; the results are similar, but the mechanisms of the device are different and, accordingly, the application features are different.
A refractor is a telescope that uses optical glass lenses. Refractors are cheaper, they have a closed tube (no dust or moisture will get into it). But the tube of such a telescope is longer: these are the structural features.
The reflector uses a mirror. Such telescopes are more expensive, but they have smaller dimensions (shorter tube). However, the telescope mirror may fade over time and the telescope may become blind.
Any telescope has its pros and cons, but for any task and budget you can find the ideal telescope model. Although, if we talk about the choice in general, mirror-lens telescopes are more versatile. - What is important when buying a telescope?
Focal length and lens diameter (aperture).
The larger the telescope tube, the larger the lens diameter will be. The larger the lens diameter, the more light assemble the telescope. The more light the telescope collects, the better dim objects will be visible and the more details will be visible. This parameter is measured in millimeters or inches.
Focal length is a parameter that affects the magnification of a telescope. If it is short (up to 7), it will be harder to get a large increase. A long focal length starts at 8 units; such a telescope will magnify more, but the viewing angle will be smaller.
This means that to observe the Moon and planets, a higher magnification is needed. Aperture (as an important parameter for the amount of light) is important, but these objects are already quite bright. But for galaxies and nebulae, it is the amount of light and aperture that are most important. - What is the magnification of a telescope?
Telescopes visually magnify an object so much that you can see details on it. The magnification will show how much you can visually enlarge something at which the observer’s gaze is directed.
The magnification of a telescope is largely limited by its aperture, that is, by the boundaries of the lens. In addition, the higher the magnification of the telescope, the darker the image will be, so the aperture must be large.
The formula for calculating magnification is: F (lens focal length) divided by f (eyepiece focal length). One telescope usually comes with several eyepieces, and the magnification ratio can thus be changed. - What can I see with a telescope?
This depends on telescope characteristics such as aperture and magnification.
So:
aperture 60-80 mm, magnification 30-125x - lunar craters from 7 km in diameter, star clusters, bright nebulae;
aperture 80-90 mm, magnification up to 200x - phases of Mercury, lunar grooves 5.5 km in diameter, rings and satellites of Saturn;
aperture 100-125 mm, magnification up to 300x - lunar craters from 3 km in diameter, clouds of Mars, stellar galaxies and nearby planets;
aperture 200 mm, magnification up to 400x - lunar craters from 1.8 km in diameter, dust storms on Mars;
aperture 250 mm, magnification up to 600x - satellites of Mars, details of the lunar surface from 1.5 km in size, constellations and galaxies. - What is a Barlow lens?
Additional optical element for a telescope. In fact, it increases the telescope's magnification several times, increasing the focal length of the lens.
The Barlow lens does work, but its capabilities are not unlimited: the lens has a physical limit to its useful magnification. After overcoming it, the image will really become larger, but the details will not be visible, only a large cloudy spot will be visible in the telescope. - What is a mount? Which mount is better?
A telescope mount is the base on which the tube is mounted. The mount supports the telescope, and its specially designed mount allows you not to rigidly mount the telescope, but also to move it along different trajectories. This will be useful, for example, if you need to monitor the movement of a celestial body.
The mount is just as important for observing as the main part of the telescope. A good mount should be stable, balance the pipe and fix it in the desired position.
There are several types of mounts: azimuth (easier and easier to set up, but difficult to keep the star in the field of view), equatorial (more difficult to set up, heavier), Dobson (a type of azimuth for floor installation), GoTo (a homing telescope mount, you just need to enter the target ).
We do not recommend the equatorial mount for beginners: it is difficult to set up and use. Azimuthal for beginners - just right. - There are Maksutov-Cassegrain and Schmidt-Cassegrain mirror-lens telescopes. Which is better?
From the point of view of application, they are approximately the same: they will show both near space, and distant, and ground objects. The difference between them is not so significant.
Due to their design, Maksutov-Cassegrain telescopes do not have side glare and their focal length is longer. Such models are considered preferable for studying planets (although this statement is practically disputed). But they will need a little more time for thermal stabilization (starting work in hot or cold conditions, when you need to equalize the temperature of the telescope and environment), and they weigh a little more.
Schmidt-Cassegrain telescopes will require less time for thermal stabilization and will weigh a little less. But they have side glare, a shorter focal length, and less contrast. - Why are filters needed?
Filters will be needed by those who want to take a closer look at the object of study and examine it better. As a rule, these are people who have already decided on a goal: near space or distant space.
There are planetary filters and deep space filters, which are optimal for studying the target. Planetary filters (for planets of the Solar System) are optimally selected in order to view a particular planet in detail, without distortion and with the best contrast. Deep sky filters (for deep space) will allow you to focus on a distant object. There are also filters for the Moon, so that you can view the earth’s satellite in all detail and with maximum convenience. There are also filters for the Sun, but we would not recommend observing the Sun through a telescope without proper theoretical and material preparation: for an inexperienced astronomer there is a high risk of vision loss. - Which manufacturer is better?
From what is presented in our store, we recommend paying attention to Celestron, Levenhuk, Sky-Watcher. There are simple models for beginners and separate additional accessories. - What can you buy in addition to the telescope?
There are options, and they depend on the wishes of the owner.
Light filters for planets or deep space - for better results and image quality.
Adapters for astrophotography - for documenting what you were able to see through the telescope.
A backpack or carrying bag - for transporting the telescope to the observation site, if it is remote. The backpack will protect fragile parts from damage and not lose small items.
Eyepieces - the optical designs of modern eyepieces differ; accordingly, the eyepieces themselves differ in price, viewing angle, weight, quality, and most importantly - focal length (and the final magnification of the telescope depends on it).
Of course, before making such purchases, it is worth checking whether the add-on is suitable for the telescope. - Where should you look through a telescope?
Ideally, to work with a telescope, you need a place with a minimum of lighting (city illumination from street lamps, illuminated advertising, light from residential buildings). If there is no known safe place outside the city, you can find a place within the city, but in a fairly dimly lit place. Clear weather will be required for any observations. It is recommended to observe deep space during the new moon (give or take a few days). A weak telescope will need a full moon - it will still be difficult to see anything further than the Moon.
Basic criteria when choosing a telescope
| Optical design. Telescopes come in mirror (reflector), lens (refractor) and mirror-lens types. | |
| Lens diameter (aperture). The larger the diameter, the greater the telescope's aperture and its resolution. Moreover, the more distant and dim objects can be seen through it. On the other hand, diameter greatly influences the dimensions and weight of a telescope (especially a lens one). It is important to remember that the maximum useful magnification of a telescope cannot physically exceed 1.4 times its diameter. Those. with a diameter of 70 mm, the maximum useful magnification of such a telescope will be ~98x. |  |
| Focal length— how far the telescope can focus. A long focal length (long focal length telescopes) means higher magnification, but a smaller field of view and aperture ratio. Suitable for detailed viewing of small, distant objects. A short focal length (short-focus telescopes) means low magnification but a large field of view. Suitable for observing extended objects such as galaxies and astrophotography. |  |
Mount is a method of attaching a telescope to a tripod.
|
Pros and cons of optical circuits
Long-focus achromat refractors (lens optical system)
Short-focus achromat refractors (lens optical system)
Long-focus reflectors (mirror optical system)
Short throw reflectors (mirror optical system)
Mirror-lens optical system (catadioptric)
Schmidt-Cassegrain (a type of mirror-lens optical design)
Maksutov-Cassegrain (a type of mirror-lens optical design)
What can you see through a telescope?
Aperture 60-80 mm
Lunar craters from 7 km in diameter, star clusters, bright nebulae.
Aperture 80-90 mm
Phases of Mercury, lunar grooves 5.5 km in diameter, rings and satellites of Saturn.
Aperture 100-125 mm
Lunar craters from 3 km to study the clouds of Mars, hundreds of star galaxies, nearby planets.
Aperture 200 mm
Lunar craters 1.8 km, dust storms on Mars.
Aperture 250 mm
Satellites of Mars, details of the lunar surface 1.5 km, thousands of constellations and galaxies with the ability to study their structure.
What device is designed to study stars and planets? A telescope, of course, but besides it, the riches of the Universe can also be seen through binoculars. And to beginning researchers celestial bodies, and experienced amateur astronomers should not neglect it. Binoculars can become the best friends of a tourist who wants to take a closer look at the celestial abyss full of stars in the evening; a city dweller looking out the window at the moon. A variety of binoculars are available at your optical supply store and are good for introducing you to the pleasure that studying the night sky can bring. John Shibley, a binocular enthusiast, has some tips for those interested in these devices and their capabilities.
Binoculars are better than telescopes for beginners
This conclusion is due to the fact that most beginners in amateur astronomy are simply not ready to fully work with a telescope. If you get completely confused in the settings, you can lose interest in the activity itself, and complex equipment parts only worsen the situation. — the device is quite simple; even with the most advanced models, difficulties usually do not arise when using it.
Pair of binoculars with different characteristics are able to provide the required level of skill in handling observation optics for the night sky. For novice astronomers, the magnification and aperture of binoculars can be sufficient to see much of what is “up there.” Even moderately powerful ones can “show” 7 times more than can be seen with the naked eye. At the same time, you can practice handling planispheres (moving maps of the starry sky) and so on.
Which binoculars should you choose to start observing the night sky?
Try to avoid the temptation - do not immediately buy a huge, super-impressive model of binoculars. This is not where you need to start. If such heavy optics are not mounted on a tripod, then at the slightest shaking of the hands it will greatly blur the image, and the starry sky will also begin to “tremble”. For beginners, the same 7x50 will be optimal; you can hold it in your hands, and the picture will not blur, but will remain clear. There is a lot to see. In addition, 7x50 binoculars are suitable for daytime use, for example for bird watching. If 7x50 is too big for you, or you are purchasing binoculars for a child, you can choose the 7x35 model.
Binoculars are great for observing the moon
When starting to explore the starry sky, most enthusiasts want to get a good look at the phases of the moon. Those interested in deep space within or beyond the Milky Way Galaxy do not usually concentrate on Earth's moon. But the Moon is an ideal target for practicing astronomical skills. To view it with binoculars, it is better to observe at dusk, then the light is not too bright and the Meadow can be seen in detail. To track the arrival of the new month, you need to look at western part sky just after sunset. At such moments, the light reflected from the Earth is clearly visible - through binoculars you can see all the details.
It also shows the phases of change, the line of sunrise and sunset on the front side earth's satellite. The lunar terminator is clearly visible through binoculars. This is the line between the light and dark parts of the star (more precisely, its day and night sides) and it is best to make observations along it. In this twilight zone, the sun is low (its angle is small) and shadows cast by relief objects can be seen on the surface of the Moon.
Also, through binoculars, ash-gray spots on the night part of the satellite are clearly visible. These are lunar seas, so called by medieval astronomers. They are now believed to have formed about 3.5 billion years ago, when asteroids colliding with the Moon caused the crust to crack. Lava leaked through the fissures and flooded the basins formed by the impacts. After cooling, it formed the gray lunar maria that can be seen today. The highlands located between them are dotted with thousands of craters, and the largest ones are also visible through binoculars. For example, near Tycho, which erupted more than 2.5 million years ago, long white traces of past events are still visible today.
https://fotoskala.ru/img/blog/big/2017/6/1/361.jpg" alt="" width="580" height="324" class="pic_frame img_zoom">Using binoculars for research Milky Way
Star clusters that are located inside our home galaxy and close to Earth are also visible through binoculars. They occupy a large area in the sky, so they can be observed not only through a telescope. Every autumn and spring, the Seven Sisters cluster, the Pleiades, appears in the sky. Only six of them are visible to the naked eye (the seventh sister, as Greek myths claimed, married a mortal and faded). Through binoculars, however, all seven are visible. Plus, like icing on the cake, there is a whole chain of stars that are nearby. The Pleiades are clearly visible because they are located relatively close - only 400 light years from Earth. They are quite young (20 million years old, while the age of the Sun is 5 billion) and are held close to each other by gravity.
Not far from the Pleiades is the constellation Orion. The Sky Hunter wears a belt of stars. If the night is clear, there are no lights or city lights nearby, then through binoculars you can see that there is also an area of luminous gas in it - the Orion Nebula, where right at the moment when you observe, a new star is being born. Another similar summer object, the Lagoon Nebula, is in the constellation Sagittarius. In its depths there are young stars that flood the gas cloud with ultraviolet radiation, causing it to glow. In a few tens of thousands of years, stellar winds will blow away these cocoons, and the new star cluster will become visible from Earth (you just need to wait).
If you look at the Milky Way through binoculars, you will see that there are hundreds of thousands of stars in it, interspersed with spherical blackened voids. These are “pockets” of gas and dust - material for building new stellar and solar systems, which are simply waiting for the moment to merge with new stars.
Looking beyond our galaxy with binoculars
Can you imagine? This is possible: in autumn and winter, a completely different galaxy is visible high in the sky of the Northern Hemisphere. An oval flare, similar to a distant star, is located near the constellation Andromeda. A galaxy similar to ours, which shines at us across all distances, can be clearly seen with binoculars. If you move away from city lights, you can even see it with the naked eye. The light traveled from Andromeda for more than 2 million years before reaching Earth. Next to it are two small “companions” - the Magellanic clouds. These are irregularly shaped galaxies with their own orbits. Someday they will break away from each other under the influence of gravity of the “parent” cluster.
It’s interesting that when many people find on the Internet this or that photograph of an astronomical deep-sky object taken by the Hubble telescope or the largest ground-based telescope, they imagine that such a picture can be seen in almost any telescope. Let me dispel this myth somewhat and dot the i’s.
I'll start with . I will name a symbolically short series of articles. I will not consider each object in detail. There are other articles on the site for this. I warn you and ask in absentia for permission to publish photographs that are not my own, taken by our guys - good astronomy lovers. If I allowed myself too much somewhere, let me know by email [email protected]. Let's figure it out.
One of the most recognizable galaxies in the northern hemisphere of the sky Andromeda's nebula (M 31 or NGC 224) in the constellation has long been considered the closest to us and thoroughly studied by scientists. In clear weather it is visible even with the naked eye or through binoculars. But if you aim a telescope with at least 150 mm, and this is already quite a semi-professional size, then:
Expectation
Reality
I note that in the photograph above, through an amateur telescope, quite a lot of details are still visible. Apparently the photo was taken on a clear night, far from city light. If the difference between the two photographs does not seem very noticeable to you, then read and look further.
The second popular and very beautiful galaxy is "Whirlpool" (M 51 or NGC 5194) in the constellation . These are actually 2 interacting galaxies (the second NGC 5195).
Expectation
Reality
The last photo shows the galaxy at about a 200 or even 250 mm telescope. Perhaps, with an ideal sky and a 150 mm telescope, you will be able to see just as well, but you shouldn’t hope for it too much.
In third place I will show you 2 galaxies in the constellation at once. I'm sure you've already guessed what we're talking about. That's right, it's a galaxy Bode (M 81 or NGC 3031) and galaxy "Cigar" (M 82 or NGC 3034). Both galaxies fit perfectly into the same field of view of the eyepiece at magnifications of 37-45x. One of them is beautiful spiral, turned towards us at an angle comfortable for observation, the other is irregular in shape and weaker in brightness. On the Internet you can find something like the following image (not to be confused with reality!)
Expectation
Reality
The last slide shows a real photograph - this is how these two interacting galaxies can be seen in a telescope with a primary mirror diameter of 200 mm.
Let's move on. Number four. Sombrero. No, I'm not talking about the Mexican wide-brimmed hat, but about the galaxy "Sombrero" (M 104 or NGC 4594) in the constellation . It is noteworthy and interesting that this is not at all one galaxy, as previously assumed, but one galaxy (flat spiral) is located inside another (elliptical). But for now it doesn’t matter to us, we want to see it as we expect.
Expectation
Reality (Are you sure you want to see this?)
Here is the cloudy area in the center of the photo, where I specifically directed the arrow - this is our desired “Sombrero” galaxy. Pam-para-ram-pam-pam... 130-150 mm telescope and typical light illumination, 10-15 kilometers from the city. Are you excited? Intrigued? Then I come to you and show you the next galaxy.
Five. Galaxy "Fireworks". Or C 12 or NGC 6946 on the border of the constellations Cygnus and Cepheus. Despite the fact that it belongs to Cygnus, you will still start your search in the sky either from the star Alderamin (α Cep) or from η (eta) Cep. Large, large, with its plane facing us, accessible through many telescope apertures.
Expectation
Reality
Here, of course, I took the liberty of showing you how it will look in a 250 mm telescope with some post-processing. What will change without this processing, you will not be able to see its color. As always, only white and shades of gray are available to you, the astronomers. Colors will be given to you by a camera that can collect as much light as you like from infinitely distant objects. The human eye is not.
If you’re not too tired yet, then this is a really worthwhile deep space object. Number six. Barred spiral galaxy in constellation NGC 2207. A powerful 250 mm telescope and a magnification of 100x will give you an amazing result that will completely change your idea of the Cosmos (I’m talking about the second image after the word “reality”):
Expectation
Reality
I’ll tell you the truth right away, it’s impossible to see like that in a 150 mm telescope. Here the distance from the city will not help you, nor the perfect black sky, nothing. A powerful telescope and these same ones weather.
Finally, I will show you the seventh galaxy. "Pinwheel" or galaxy "Spinner" (M 101 or NGC 5457) in the constellation . This is that unfortunate galaxy that has been hiding from me all my life (I recently saw it, it would be better if I didn’t do this), I have talked about it more than once in articles about observations, for example, or . Let's see what it's like on the Internet and compare it with reality.
Expectation
Reality
Having found the last photograph, I realized that this is exactly how it is seen in 200 and even 250 mm telescopes. Under red arrow see the subtle spiral structure of the galaxy? If not, tilt the monitor or look with peripheral vision.
Well, dear space gourmets, is reality deceptive or maybe your expectations are too high? In any case, I am convinced that anyone who really cares about space, looking at the photographs under the inscription "Reality", enjoys it! I am not saying that this is how you will see galaxies through your telescope. Someone is a little better, more contrasting, clearer, the brain will think of something for you and decide: here it’s dark, here the brightness increases, the eye will discern heterogeneity; but someone will not be impressed by such a beautiful representation of star cities. Those who don’t know, go down to the ground, look through the telescope’s eyepiece, compare with the image of the Hubble telescope on the Internet. Be attentive and self-critical.
Perhaps I’ll stop on this rhetorical note and give some time to rethink...
P.S. The article is extremely positive and in no way turns beginners against observations; on the contrary, it gives an impetus to how so much useful information can be extracted from a seen “blurry spot” or a pair of bright stars.
All articles in the series "Expectation and Reality".
Any person who is thinking about buying a telescope asks himself the question - what can I see through it? Unfortunately, there is no 100% accurate answer to this question, because... the way you see the treasures of the starry sky through a telescope is influenced by many factors: illumination from street lamps, smog in large cities, the quality of the instrument itself and, in the end, the experience of the observer plays a significant role.
However, the following table will help answer this question in general terms:
| Telescope | Moon, planets and their satellites | Stars | Nebulae, galaxies and star clusters |
|
60-70mm refractor, magnification from 25 to 125x. |
Spots on the sun (a solar filter is required), phases of Venus, lunar craters with a diameter of 7-10 km, cloud bands on Jupiter and 4 of its satellites, rings of Saturn and, under good conditions, the Cassini gap, Uranus and Neptune in the form of small greenish stars. | Double stars, the distance between which is more than 2 arcseconds, the maximum accessible magnitude is 11.5. | Large globular star clusters, bright nebulae. In fact, under good observing conditions, all Messier objects are accessible to such an instrument. |
|
80-90mm refractor, 100-115mm reflector, magnification from 15 to 250x |
Structure sunspots, phases of Mercury, lunar grooves and craters with a diameter of 5.5 km, polar caps on Mars, as well as continents in the form of dark spots during great oppositions, additional stripes on Jupiter, shadows from its satellites on the surface, the Cassini gap in the rings of Saturn is constantly visible, plus 5 of its satellites, Uranus and Neptune in the form of tiny disks. | Double stars, the distance between which is more than 1.5 arcseconds, the maximum accessible magnitude is 12. | Several dozen globular clusters, diffuse and planetary nebulae, galaxies. All Messier objects, the brightest NGCs under good conditions, and details of the structure of many nebulae are also available, but the galaxies remain featureless gray blobs. |
| 100-125mm refractor, 150mm reflector, magnification from 30 to 300x | Many formations on the moon, circuses, grooves, craters with a diameter of 3 km, more dark spots (continents) on Mars, details in the structure of the clouds of Jupiter, cloud bands on Saturn, many faint comets and asteroids | Double stars, the distance between which is more than 1 arcseconds (under good conditions), the maximum accessible magnitude is 13. | Hundreds of star clusters, nebulae, galaxies (some with hints of spiral structure), many NGC/IC catalog objects in good conditions. Structure of nebulae and star clusters. |
|
150-175mm refractor, 200mm reflector, 175-225mm catadioptric telescope, magnification from 50 to 400x |
Moon formations less than 1.8 km in diameter, large clouds and dust storms on Mars, 6-7 satellites of Saturn, with high magnification the 4 brightest satellites of Jupiter are visible as tiny disks, many faint asteroids in the form of small stars. | Double stars, the distance between which is less than 1 arcseconds (under good conditions), the maximum accessible magnitude is 14. | Many globular clusters break up into individual stars right up to the center, there are many details in the structure of nebulae, and the structure of many galaxies is visible. |
| 250 mm (or more) reflector and catadioptric | Most often, atmospheric interference prevents more detail from being seen in solar system objects, even as the telescope's aperture increases. But during the period when the atmosphere is transparent and calm, details of the lunar surface with a diameter of less than 1.5 km, small details on the surface of Mars are visible, and sometimes it is possible to see its satellites - Phobos and Deimos, subtle structures of the cloud cover of Jupiter, the Encke division in the rings of Saturn, the satellite of Neptune Triton, Pluto may be visible as a small star. | Double stars, the distance between which is 0.5 arc seconds (under good conditions), the maximum accessible magnitude is 14.5 (and higher). | Thousands of globular and open star clusters; the NGC/IC catalog is virtually fully accessible; details of the structure of galaxies and nebulae that are not discernible using weaker instruments; Some objects have noticeable color. |
What types of telescopes are there and what is the difference?
All telescopes - both professional and amateur - are divided according to the type of optical design into three large groups:
- reflectors;
- refractors:
- catadioptrics.
In reflectors, they are used to collect light. mirror. In refractors - lenses. And catadioptrics contain as optical elements both mirrors and lenses.
The main difference between all telescopes on the amateur market is the diameter of the lens. The diameter of a telescope is usually called the “aperture”. The larger the aperture, the larger and heavier the telescope itself, but also the more you can see through it. Aperture is usually measured in millimeters and inches. The diameters of commercially available telescopes range from 70mm to 400mm. That is, these are the telescopes that can be purchased at astronomy stores.
The range of apertures available to the hobbyist for each optical design is approximately the following:
- refractors - from 50 to 150 mm;
- reflectors - from 100 mm to 400 mm;
- catadioptrics - from 90 mm to 400 mm.
What can you see at different apertures?
It’s worth warning here that what you see through your first telescope will be very different from the photographs you saw on the Internet. Objects of observation are usually divided into objects of the solar system - the Moon, Sun, planets and comets, and deep space objects (deep sky) - star clusters, double stars, nebulae, galaxies, globular clusters.
With the Moon and the Sun everything is obvious, this large objects and are clearly visible. The planets are visible in color and with varying amounts of detail depending on the aperture of the telescope. From the picture below you can estimate the apparent sizes of the planets relative to each other, as well as an example of how Mars is visible at different apertures.
Deep space objects are another matter. Due to the nature of our vision, most of them will be black and white and look like gray foggy spots. But the color of individual stars is clearly visible; it can be bluish, orange and white. And also several nebulae have a hint of color in relatively large telescopes. Below, as an example, are sketches of observers - approximately how our eye sees an object through a telescope. On the right are photographs of the same objects for comparison.
Let's take a quick look through the aperture row and see what we can see.
60-70 mm:
- Sun spots
- Phases of Mercury and Venus
- Some details on Mars
- 2 main belts on Jupiter and the Great Red Spot (GRS), four satellites of Jupiter
- Rings of Saturn
80-100mm:
- Sun spots
- Phases of Mercury and Venus
- Polar caps and seas on Mars during oppositions.
- Several belts on Jupiter and the Great Red Spot (GRS), four moons of Jupiter
- Rings of Saturn, Cassini slit under excellent visibility conditions
- Uranus and Neptune either as stars or as small disks with no details on them
- All or almost all Messier catalog objects with a minimum amount of detail in them
150-200mm:
- Numerous details on Mars during oppositions
- Details in the belts of Jupiter
- Cloud belts on Saturn
- Many weak asteroids and comets
- Hundreds of star clusters, nebulae and galaxies (you can see traces of a spiral structure in the brightest galaxies)
- A large number of NGC catalog objects (many objects have interesting details)
250 mm or more:
- Small clouds and small structures on Mars
- A large amount of detail in the atmosphere of Jupiter
- Encke division in the rings of Saturn, disk of Titan
- Neptune's moon Triton
- Thousands of galaxies, globular clusters and nebulae
- Virtually all objects in the NGC catalog, many of which show details not visible in smaller telescopes
- Subtle colors are observed in the brightest nebulae
It is clear that the larger the telescope, the better, but the larger, heavier and more expensive it is.
Which brands of telescopes should I buy?
In this regard, it is worth keeping the following in mind: most of the affordable models on the market are of floating quality due to the complexity of manufacturing and setting up precise optics for little money. Therefore, there is some kind of lottery. Despite this, even unsuccessful devices are capable of showing enough with the only limitation that they cannot be used at the highest magnifications. Most often, the telescope may not reveal its capabilities due to lack of proper alignment (adjusting the mirror alignment), that is, due to the inexperience of the telescope user.
Telescopes that have more or less guaranteed quality are, accordingly, more expensive, and the range of models available for sale is rapidly falling. Devices having 100% guaranteed quality They cost, as they say, completely different money, and are rarely available for free sale in Russia.
Please note that most of them are located in China and Taiwan, but there is some quality of Chinese products.
Now let's look at telescopes that can be found, for example, on supermarket shelves somewhere between tomatoes and TVs:
What should you pay attention to when buying a telescope?
Checking the quality of optics on site is almost an impossible task for a beginner. The optics are checked either at night using the image of a star, or on the so-called “optical bench”. Therefore, all you need to check when purchasing is the absence of scratches on the optics, completeness and mechanical integrity.
What accessories are needed for a telescope?
The advice is this - it is better to invest in the telescope itself at the beginning, rather than accessories. Since at the initial stage there will be a lot of worries with mastering the telescope and the included accessories will be enough. And so, with a minimum budget, you can purchase a special eyepiece for planets, which provides maximum useful magnification, and a solar film filter. With an average budget and the ability to travel to good sky You can purchase additional filters for deep - UHC, OIII, H-beta.
Briefly about the conditions for effective observations
If you buy a good frying pan, you won't good cook. So here too - you need to learn how to realize the potential of the telescope.
- Instrument condition: the reflector must be well adjusted and checked by the star: for such a telescope, the stars in the center of the field should be points, and at the edges they should acquire small cometary tails towards the edges.
- Thermal stabilization: The larger the telescope, the longer it takes to cool down. For large apertures, fans must be used.
- Deep observation: To see deep space objects, you need to travel outside the city, where there is a dark sky without light.
- Light adaptation: In order not to spoil it and not to step on the foot of a fellow hobbyist, you need to use red lanterns.
- Good atmosphere: observations should not be interfered with by heat flows from buildings, the atmosphere should be free of haze and suspension. In the case of observing planets, the flowing atmosphere can completely “blur” it. An absolutely calm atmosphere is extremely rare. As a rule, you have to look at the planet for a long time to catch a moment of calm and see more details. Therefore, watching from a warm balcony, out a window, or even through a double-glazed window is a very bad idea.
- Position of the object in the sky: The height of the object above the horizon is important. The lower the object, the thicker the atmospheric layer, the worse the image. The planets have orange and blue disk colors, and no details are visible at all.
- Dew protection: To prevent mirrors and lenses from fogging up, it is necessary to organize heating.
Astrophotography
To become a simple photographer, all you need to do now is buy a camera and press the shutter button. Perhaps this is why the illusion is created that taking photos of astronomical objects is just as easy. Beginners can imagine it something like this:
But in fact, the astrophoto kit looks like this:
In a nutshell, this is an expensive and time-consuming pleasure; it is strictly divided into planetary astrophotography and astrophotography of deep space objects, and so that you understand that it is not enough to press the shutter button, I will briefly describe the process.
For astrophotography of planets, a special video camera or even a webcam is required, a video is shot for several minutes, the best frames are selected from this video, which are processed into a frame addition program. At the output we get something that we further refine in a graphic editor.
For deep astrophotography, a special or SLR camera is used, a very powerful and stable mount (tripod) and the object is photographed at a long exposure for 1-20 minutes. In this way, a certain number of frames are collected with a total exposure of several hours or several tens of hours, and the frames are put together.
If you still want to get into astrophotography, then remember that you will have to choose - either your telescope will be visual and not well suited for astrophotography, or it will be a telescope that is only good for astrophotography.
