How to make a reliable and powerful telescope yourself at home. Detailed diagrams for assembling the structure - a do-it-yourself refracting telescope from scrap materials. How to make a spyglass: step-by-step instructions

It's safe to say that everyone has dreamed of taking a closer look at the stars. You can use binoculars or a spotting scope to admire the bright night sky, but you are unlikely to be able to see anything in detail through these devices. Here you will need more serious equipment - a telescope. To have such a miracle of optical technology at home, you need to pay a large sum, which not all lovers of beauty can afford. But don't despair. You can make a telescope with your own hands, and for this, no matter how absurd it may sound, you don’t have to be a great astronomer and designer. If only there was a desire and an irresistible craving for the unknown.

Why should you try making a telescope?

We can definitely say that astronomy is a very complex science. And it requires a lot of effort from the person doing it. A situation may occur that you purchase an expensive telescope, and the science of the Universe will disappoint you, or you simply realize that this is not your thing at all.

In order to figure out what’s what, it’s enough to make a telescope for an amateur. Observing the sky through such a device will allow you to see many times more than through binoculars, and you will also be able to figure out whether this activity is interesting to you. If you are passionate about studying the night sky, then, of course, you cannot do without a professional apparatus.

What can you see with a homemade telescope?

Descriptions of how to make a telescope can be found in many textbooks and books. Such a device will allow you to clearly see the lunar craters. With it you can see Jupiter and even make out its four main satellites. The rings of Saturn, familiar to us from the pages of textbooks, can also be seen using a telescope made by ourselves. In addition, many more celestial bodies can be seen with your own eyes, for example, Venus, a large number of stars, clusters, nebulae.

A little about the telescope design

The main parts of our unit are its lens and eyepiece. With the help of the first part, the light emitted by celestial bodies is collected. How distant bodies can be seen, as well as the magnification of the device, depends on the diameter of the lens. The second member of the tandem, the eyepiece, is designed to enlarge the resulting image so that our eye can admire the beauty of the stars.

Now about the two most common types of optical devices - refractors and reflectors. The first type has a lens made of a lens system, and the second has a mirror lens. Lenses for a telescope, unlike a reflector mirror, can be found quite easily in specialized stores. Buying a mirror for a reflector will not be cheap, and making one yourself will be impossible for many. Therefore, as has already become clear, we will be assembling a refractor, and not a reflecting telescope. Let's finish the theoretical excursion with the concept of telescope magnification. It is equal to the ratio of the focal lengths of the lens and eyepiece.

How to make a telescope? We select materials

In order to start assembling the device, you need to stock up on a 1-diopter lens or its blank. By the way, such a lens will have a focal length of one meter. The diameter of the blanks will be about seventy millimeters. It should also be noted that it is better not to choose spectacle lenses for a telescope, since they generally have a concave-convex shape and are poorly suited for a telescope, although if you have them on hand, you can use them. It is recommended to use long-focal lenses with a biconvex shape.

As an eyepiece, you can take a regular magnifying glass with a thirty-millimeter diameter. If it is possible to get an eyepiece from the microscope, then it is certainly worth taking advantage of. It is also perfect for a telescope.

What should we make the housing for our future optical assistant from? Two pipes of different diameters made of cardboard or thick paper are perfect. One (the shorter one) will be inserted into the second, with a larger diameter and longer. A pipe with a smaller diameter should be made twenty centimeters long - this will ultimately be the eyepiece unit, and it is recommended to make the main one a meter long. If you don’t have the necessary blanks at hand, it doesn’t matter, the body can be made from an unnecessary roll of wallpaper. To do this, the wallpaper is wound in several layers to create the required thickness and rigidity and glued. How to make the diameter of the inner tube depends on what kind of lens we use.

Telescope stand

A very important point in creating your own telescope is preparing a special stand for it. Without it, it will be almost impossible to use it. There is an option to install the telescope on a camera tripod, which is equipped with a moving head, as well as fasteners that will allow you to fix different positions of the body.

Telescope assembly

The lens for the lens is fixed in a small tube with its convex outward. It is recommended to fasten it using a frame, which is a ring similar in diameter to the lens itself. Directly behind the lens, further along the pipe, it is necessary to equip a diaphragm in the form of a disk with a thirty-millimeter hole exactly in the middle. The purpose of the aperture is to eliminate image distortion caused by the use of a single lens. Also, installing it will affect the reduction of light that the lens receives. The telescope lens itself is mounted near the main tube.

Naturally, the eyepiece assembly cannot do without the eyepiece itself. First you need to prepare fastenings for it. They are made in the form of a cardboard cylinder and are similar in diameter to an eyepiece. The fastening is installed inside the pipe using two disks. They are the same diameter as the cylinder and have holes in the middle.

Setting up the device at home

The image must be focused using the distance from the lens to the eyepiece. To do this, the eyepiece assembly moves in the main tube. Since the pipes must be well pressed together, the required position will be securely fixed. It is convenient to perform the tuning process on large bright bodies, for example, the Moon; a neighboring house will also work. When assembling, it is very important to ensure that the lens and eyepiece are parallel and their centers are on the same straight line.

Another way to make a telescope with your own hands is to change the size of the aperture. By varying its diameter, you can achieve the optimal picture. Using optical lenses of 0.6 diopters, which have a focal length of approximately two meters, you can increase the aperture and make the zoom much closer on our telescope, but you should understand that the body will also increase.

Watch out - Sun!

By the standards of the Universe, our Sun is far from the brightest star. However, for us it is a very important source of life. Naturally, having a telescope at their disposal, many will want to take a closer look at it. But you need to know that this is very dangerous. After all, sunlight, passing through the optical systems we have built, can be focused to such an extent that it will be able to burn through even thick paper. What can we say about the delicate retina of our eyes?

Therefore, you need to remember a very important rule: you cannot look at the Sun through zooming devices, especially a home telescope, without special protective equipment. Such means are considered to be light filters and a method of projecting an image onto a screen.

What if you couldn’t assemble a telescope with your own hands, but you really want to look at the stars?

If for some reason it is impossible to assemble a homemade telescope, then do not despair. You can find a telescope in a store for a reasonable price. The question immediately arises: “Where are they sold?” Such equipment can be found in specialized astro-device stores. If there is nothing like this in your city, then you should visit a photographic equipment store or find another store that sells telescopes.

If you are lucky - there is a specialized store in your city, and even with professional consultants, then this is definitely the place for you. Before going, it is recommended to look at an overview of telescopes. First, you will understand the characteristics of optical devices. Secondly, it will be more difficult to deceive you and slip you a low-quality product. Then you will definitely not be disappointed in your purchase.

A few words about buying a telescope through the World Wide Web. This type of shopping is becoming very popular nowadays, and it is possible that you will use it. It’s very convenient: you look for the device you need, and then order it. However, you may come across the following nuisance: after a long selection, it may turn out that the product is no longer in stock. A much more unpleasant problem is the delivery of goods. It is no secret that a telescope is a very fragile thing, so only fragments can be delivered to you.

It is possible to purchase a telescope by hand. This option will allow you to save a lot of money, but you should be well prepared so as not to buy a broken item. A good place to find a potential seller is astronomer forums.

Price per telescope

Let's look at some price categories:

About five thousand rubles. Such a device will correspond to the characteristics of a telescope made with your own hands at home.

Up to ten thousand rubles. This device will certainly be more suitable for high-quality observation of the night sky. The mechanical part of the body and equipment will be quite poor, and you may have to spend money on some spare parts: eyepieces, filters, etc.

From twenty to one hundred thousand rubles. This category includes professional and semi-professional telescopes. Surely a beginner will have no need for a mirror camera with an astronomical cost. This is simply, as they say, a waste of money.

Conclusion

As a result, we got acquainted with important information about how to make a simple telescope with your own hands, and some of the nuances of buying a new device for observing the stars. In addition to the method that we have considered, there are others, but this is a topic for another article. Whether you've built a telescope at home or purchased a new one, astronomy will take you into the unknown and provide experiences you've never experienced before.

Sometimes you find all sorts of rubbish in your bins. In dresser drawers in the country, in chests in the attic, among things under an old sofa. Here are grandma's glasses, here is a folding magnifying glass, here is a damaged peephole from the front door, and here are a bunch of lenses from disassembled cameras and overhead projectors. It’s a shame to throw it away, and all this optics sits idle, just taking up space.
If you have the desire and time, then try to make a useful thing out of this trash, for example, a spyglass. Do you want to say that you’ve already tried it, but the formulas in the help books turned out to be painfully complicated? Let's try again, using simplified technology. And everything will work out for you.
Instead of guessing by eye what will happen, we will try to do everything further according to science. Lenses are magnifying and minimizing. Let's divide all the available lenses into two piles. In one group there are magnifying ones, in the other group there are diminutive ones. The disassembled peephole from the door has both magnifying and minimizing lenses. Such small lenses. They will be useful to us too.
Now we will test all magnifying lenses. To do this, you need a long ruler and, of course, a piece of paper for notes. It would be nice if the sun was still shining outside the window. With the sun, the results would be more accurate, but a burning light bulb will do. We test lenses as follows:
-Measure the focal length of the magnifying lens. We place the lens between the sun and the piece of paper, and moving the piece of paper away from the lens or the lens away from the piece of paper, we find the smallest point of convergence of the rays. This will be the focus length. We measure it (focus) on all lenses in millimeters and write down the results, so that later we don’t have to worry about determining the suitability of the lens.
So that everything continues to be scientific, we remember a simple formula. If 1000 millimeters (one meter) is divided by the focal length of the lens in millimeters, we get the lens power in diopters. And if we know the diopters of the lenses (from an optics store), then dividing the meter by diopters we get the focal length. Diopters on lenses and magnifying glasses are indicated by a multiplication symbol immediately after the number. 7x; 5x; 2.5x; etc.
Such testing will not work with miniature lenses. But they are also designated in diopters and also have a focus according to diopters. But the focus will already be negative, but not at all imaginary, quite real, and we will now be convinced of this.
Let's take the longest focal length magnifying lens in our kit and combine it with the strongest reducing lens. The total focal length of both lenses will immediately decrease. Now let's try to look through both lenses assembled, diminutive to ourselves.
Now we slowly move the magnifying lens away from the diminutive lens, and in the end, perhaps, we will get a slightly enlarged image of objects outside the window.
The mandatory condition here must be the following. The focus of the diminutive (or negative) lens must be smaller than the magnifying (or positive) lens.
Let's introduce new concepts. The positive lens, also known as the front lens, is also called the objective lens, and the negative or rear lens, the one closer to the eye, is called the eyepiece. The power of the telescope is equal to the focal length of the lens divided by the focal length of the eyepiece. If the division results in a number greater than one, then the telescope will show something; if it is less than one, then you will not see anything through the telescope.
Instead of a negative lens, short-focus positive lenses can be used in eyepieces, but the image will already be inverted and the telescope will be slightly longer.
By the way, the length of the telescope is equal to the sum of the focal lengths of the lens and eyepiece. If the eyepiece is a positive lens, then the focus of the eyepiece is added to the focus of the lens. If the eyepiece is made of a negative lens, then plus to minus is equal to minus and from the focus of the lens, the focus of the eyepiece is already subtracted.
This means the basic concepts and formulas are as follows:
-Lens focal length and diopter.
-Magnification of the telescope (the focus of the lens is divided by the focus of the eyepiece).
-The length of the telescope (the sum of the focal points of the lens and eyepiece).
THAT'S THE COMPLEXITY!!!
Now a little more technology. Remember, probably, that telescopes are made folding, from two, three or more parts - elbows. These knees are made not only for convenience, but also for specific adjustment of the distance from the lens to the eyepiece. Therefore, the maximum length of the telescope is slightly greater than the sum of the focuses, and the moving parts of the telescope allow you to adjust the distance between the lenses. Plus and minus to the theoretical pipe length.
The lens and eyepiece must be on the same (optical) axis. Therefore, there should be no looseness of the pipe elbows relative to each other.
The inner surface of the tubes must be painted matte (not shiny) black, or the inner surface of the tube can be covered with black (painted) paper.
It is desirable that the internal cavity of the telescope be sealed, then the pipe will not sweat inside.
And the last two tips:
-don’t get carried away with large magnifications.
-if you want to make a homemade telescope, then my explanations will probably not be enough for you, read special literature.
If you don’t understand what’s what in one book, take another, third, fourth, and in some book you will still get the answer to your question. If it happens that you don’t find the answer in books (or on the Internet), then Congratulations! You have reached a level where the answer is already expected from YOU.
I found a very interesting article on the Internet on the same topic:
http://herman12.narod.ru/Index.html
A good addition to my article is offered by the author from prozy.ru Kotovsky:
So that even such a small amount of work does not go to waste, we should not forget about the diameter of the lens, on which the exit pupil of the device depends, calculated as the diameter of the lens divided by the magnification of the tube.
For a telescope, the exit pupil can be about a millimeter. This means that from a lens with a diameter of 50 mm you can squeeze (by choosing a suitable eyepiece) 50x magnification. At higher magnification, the image will deteriorate due to diffraction and lose brightness.
For a “terrestrial” tube, the exit pupil must be at least 2.5 mm (preferably larger. The BI-8 army binoculars have 4 mm). Those. for “terrestrial” use, you should not squeeze more than 15-20x magnification from a 50 mm lens. Otherwise, the picture will darken and blur.
It follows from this that lenses with a diameter of less than 20 mm are not suitable for the lens. Perhaps 2-3x magnification is enough for you.
In general, a lens made from spectacle lenses is not comme il faut: meniscus distortions due to convex-concave. There must be a duplex lens, or even a triplex if it is short-focus. You can't just find a good lens among the trash. Perhaps there’s a “photo gun” lens lying around (super!), a ship’s collimator or an artillery rangefinder :)
About eyepieces. For a Galilean tube (an eyepiece with a diverging lens), you should use a diaphragm (a circle with a hole) with a diameter equal to the calculated size of the exit pupil. Otherwise, when the pupil moves away from the optical axis, there will be severe distortion. For a Kepler tube (converging eyepiece, the image is inverted), single-lens eyepieces produce large distortions. You need at least a two-lens Huygens or Ramsden eyepiece. Better prepared - from a microscope. As a last resort, you can use a camera lens (don't forget to fully open the blade aperture!)
About the quality of lenses. Everything from the door peepholes goes into the trash! From the remaining ones, choose lenses with anti-reflective coating (characteristic purple reflection). The absence of clearing is allowed on surfaces facing outward (toward the eye and the object of observation). The best lenses are from optical instruments: film cameras, microscopes, binoculars, photo enlargers, slide projectors - at worst. Don’t rush to disassemble finished eyepieces and objectives made from several lenses! It is better to use the whole thing - everything is selected in the best possible way.
And further. At high magnifications (>20) it is difficult to do without a tripod. The picture is dancing - you can’t make out anything.
You should not try to make the pipe shorter. The longer the focal length of the lens (more precisely, its ratio to the diameter), the lower the requirements for the quality of all optics. This is why in the old days telescopes were much longer than modern binoculars.

I made the best homemade trumpet this way: a long time ago in Salavat I bought a cheap children's toy - a plastic spyglass (Galileo). She had 5x magnification. But she had a duplex lens with a diameter of almost 50 mm! (Apparently, substandard from the defense industry).
Much later, I purchased an inexpensive, small Chinese 8x monocular with a 21mm lens. There is a powerful eyepiece and a compact wrapping system on prisms with a “roof”.
I "crossed" them! I removed the eyepiece from the toy and the lens from the monocular. Folded, stapled. The inside of the toy was previously covered with black velvet paper. Got a powerful 20x compact pipe of high quality.

A spyglass is considered to be an ancient object, the use of which allows you to easily view objects located at a long distance. But, having learned the basics of how to make a telescope yourself, you can become the owner of this wonderful optical device, to which the Age of Great Geographical Discoveries owes a lot. By the way, a telescope made at home is suitable not only for entertaining children, but can also become a good tool for ground observation. It is worth saying that homemade telescopes cope with presenting a straight, rather than inverted, image. The entire process of creating this optical instrument includes step-by-step work, as well as having at hand an arsenal of all the necessary items that you cannot do without in the work process.

So, first of all, you need to start selecting lenses. Here, glasses from magnifying glasses may well be suitable for this purpose. By the way, you can purchase them at any store specializing in optics. As for these glasses, the diopter of one of them should be from +4 to +6, and the second from -18 to -21. In terms of diameter, a positive lens should be 5 centimeters, and a negative lens should be 1-3 centimeters. Having obtained the necessary lenses, you need to take a block of wood in the form of a cylinder (it is important that its diameter fully matches the diameter of the negative lens), onto which a single layer of plastic film is then wound. You can secure the polyethylene with tape. If, unfortunately, polyethylene is not at hand, it is replaced with a simple bag, which everyone probably has at home.

The film is wrapped on top with a tube of paper, the layers of which must be well coated with glue. The pipe must have a length of 126 millimeters. But its outer diameter must completely correspond to the diameter of the objective lens, which is positive. Now the future creation is removed from the blank and left for some time so that it dries well. As the glue dries, the pipe will harden, and once it is completely hardened, it is wrapped in another layer of plastic film and secured with tape. But this process needs to be repeated all over again by wrapping the pipe with paper and glue. This must be done in such a way that the walls are 3-4 millimeters thick, while the length of the outer pipe should be 126 millimeters. The outer part must be removed from the inner part and left for the glue to dry completely.

Now it's time to get rid of the polyethylene. To do this, the inner pipe is placed inside the outer one. At this moment, the smaller element should have a larger stroke inside with a separate level of friction. If there is no friction, the outer diameter of the smaller pipe should be increased by using a couple of layers of thin paper. Now the pipes are disconnected, and the surfaces inside are coated with matte black paint. To make an eyepiece, you need to glue two identical paper rings together. A wooden block will significantly facilitate the gluing process. The rings must have an outer diameter equal to the inner diameter of the small pipe. When measured, the wall thickness will be 2 millimeters, and the elevation will be 3 millimeters. Paint of the same color is also applied to the rings, or you can use black paper to make them.

The eyepiece should be assembled following a certain sequence. At one end, the inner surface of the small pipe is smeared with glue (you need to lubricate about 2 cm). Next, the first ring is inserted, and then a small lens, and only then the second ring is inserted. Once the eyepiece has dried, you should move on to creating the lens. To do this, make two more rings from paper with a diameter equal to the diameter of the larger lens. A circle is cut out of thin cardboard, which corresponds to the size of the lens, and a hole with a diameter of about 3 centimeters is pierced inside it. The place where the circle is glued is the end of one of the rings. Black paint is applied to the rings, after which the lens is assembled according to the principle of assembling an eyepiece. The only difference is that initially a ring with a glued circle is inserted into the pipe, which is turned inward of the pipe. The hole will become the diaphragm. At the end, put a lens with a second ring and let the pipe dry.

It's safe to say that everyone has dreamed of taking a closer look at the stars. You can use binoculars or a spotting scope to admire the bright night sky, but you are unlikely to be able to see anything in detail through these devices. Here you will need more serious equipment - a telescope. To have such a miracle of optical technology at home, you need to pay a large sum, which not all lovers of beauty can afford. But don't despair. You can make a telescope with your own hands, and for this, no matter how absurd it may sound, you don’t have to be a great astronomer and designer. If only there was a desire and an irresistible craving for the unknown.

Why should you try making a telescope?

We can definitely say that astronomy is a very complex science. And it requires a lot of effort from the person doing it. A situation may occur that you purchase an expensive telescope, and the science of the Universe will disappoint you, or you simply realize that this is not your thing at all.

In order to figure out what’s what, it’s enough to make a telescope for an amateur. Observing the sky through such a device will allow you to see many times more than through binoculars, and you will also be able to figure out whether this activity is interesting to you. If you are passionate about studying the night sky, then, of course, you cannot do without a professional apparatus.

What can you see with a homemade telescope?

Descriptions of how to make a telescope can be found in many textbooks and books. Such a device will allow you to clearly see the lunar craters. With it you can see Jupiter and even make out its four main satellites. The rings of Saturn, familiar to us from the pages of textbooks, can also be seen using a telescope made by ourselves. In addition, many more celestial bodies can be seen with your own eyes, for example, Venus, a large number of stars, clusters, nebulae.

A little about the telescope design

The main parts of our unit are its lens and eyepiece. With the help of the first part, the light emitted by celestial bodies is collected. How distant bodies can be seen, as well as the magnification of the device, depends on the diameter of the lens. The second member of the tandem, the eyepiece, is designed to enlarge the resulting image so that our eye can admire the beauty of the stars.

Now about the two most common types of optical devices - refractors and reflectors. The first type has a lens made of a lens system, and the second has a mirror lens. Lenses for a telescope, unlike a reflector mirror, can be found quite easily in specialized stores. Buying a mirror for a reflector will not be cheap, and making one yourself will be impossible for many. Therefore, as has already become clear, we will be assembling a refractor, and not a reflecting telescope. Let's finish the theoretical excursion with the concept of telescope magnification. It is equal to the ratio of the focal lengths of the lens and eyepiece.

How to make a telescope? We select materials

In order to start assembling the device, you need to stock up on a 1-diopter lens or its blank. By the way, such a lens will have a focal length of one meter. The diameter of the blanks will be about seventy millimeters. It should also be noted that it is better not to choose spectacle lenses for a telescope, since they generally have a concave-convex shape and are poorly suited for a telescope, although if you have them on hand, you can use them. It is recommended to use long-focal lenses with a biconvex shape.

As an eyepiece, you can take a regular magnifying glass with a thirty-millimeter diameter. If it is possible to get an eyepiece from the microscope, then it is certainly worth taking advantage of. It is also perfect for a telescope.

What should we make the housing for our future optical assistant from? Two pipes of different diameters made of cardboard or thick paper are perfect. One (the shorter one) will be inserted into the second, with a larger diameter and longer. A pipe with a smaller diameter should be made twenty centimeters long - this will ultimately be the eyepiece unit, and it is recommended to make the main one a meter long. If you don’t have the necessary blanks at hand, it doesn’t matter, the body can be made from an unnecessary roll of wallpaper. To do this, the wallpaper is wound in several layers to create the required thickness and rigidity and glued. How to make the diameter of the inner tube depends on what kind of lens we use.

Telescope stand

A very important point in creating your own telescope is preparing a special stand for it. Without it, it will be almost impossible to use it. There is an option to install the telescope on a camera tripod, which is equipped with a moving head, as well as fasteners that will allow you to fix different positions of the body.

Telescope assembly

The lens for the lens is fixed in a small tube with its convex outward. It is recommended to fasten it using a frame, which is a ring similar in diameter to the lens itself. Directly behind the lens, further along the pipe, it is necessary to equip a diaphragm in the form of a disk with a thirty-millimeter hole exactly in the middle. The purpose of the aperture is to eliminate image distortion caused by the use of a single lens. Also, installing it will affect the reduction of light that the lens receives. The telescope lens itself is mounted near the main tube.

Naturally, the eyepiece assembly cannot do without the eyepiece itself. First you need to prepare fastenings for it. They are made in the form of a cardboard cylinder and are similar in diameter to an eyepiece. The fastening is installed inside the pipe using two disks. They are the same diameter as the cylinder and have holes in the middle.

Setting up the device at home

The image must be focused using the distance from the lens to the eyepiece. To do this, the eyepiece assembly moves in the main tube. Since the pipes must be well pressed together, the required position will be securely fixed. It is convenient to perform the tuning process on large bright bodies, for example, the Moon; a neighboring house will also work. When assembling, it is very important to ensure that the lens and eyepiece are parallel and their centers are on the same straight line.

Another way to make a telescope with your own hands is to change the size of the aperture. By varying its diameter, you can achieve the optimal picture. Using optical lenses of 0.6 diopters, which have a focal length of approximately two meters, you can increase the aperture and make the zoom much closer on our telescope, but you should understand that the body will also increase.

Watch out - Sun!

By the standards of the Universe, our Sun is far from the brightest star. However, for us it is a very important source of life. Naturally, having a telescope at their disposal, many will want to take a closer look at it. But you need to know that this is very dangerous. After all, sunlight, passing through the optical systems we have built, can be focused to such an extent that it will be able to burn through even thick paper. What can we say about the delicate retina of our eyes?

Therefore, you need to remember a very important rule: you cannot look at the Sun through zooming devices, especially a home telescope, without special protective equipment. Such means are considered to be light filters and a method of projecting an image onto a screen.

What if you couldn’t assemble a telescope with your own hands, but you really want to look at the stars?

If for some reason it is impossible to assemble a homemade telescope, then do not despair. You can find a telescope in a store for a reasonable price. The question immediately arises: “Where are they sold?” Such equipment can be found in specialized astro-device stores. If there is nothing like this in your city, then you should visit a photographic equipment store or find another store that sells telescopes.

If you are lucky - there is a specialized store in your city, and even with professional consultants, then this is definitely the place for you. Before going, it is recommended to look at an overview of telescopes. First, you will understand the characteristics of optical devices. Secondly, it will be more difficult to deceive you and slip you a low-quality product. Then you will definitely not be disappointed in your purchase.

A few words about buying a telescope through the World Wide Web. This type of shopping is becoming very popular nowadays, and it is possible that you will use it. It’s very convenient: you look for the device you need, and then order it. However, you may come across the following nuisance: after a long selection, it may turn out that the product is no longer in stock. A much more unpleasant problem is the delivery of goods. It is no secret that a telescope is a very fragile thing, so only fragments can be delivered to you.

It is possible to purchase a telescope by hand. This option will allow you to save a lot of money, but you should be well prepared so as not to buy a broken item. A good place to find a potential seller is astronomer forums.

Price per telescope

Let's look at some price categories:

About five thousand rubles. Such a device will correspond to the characteristics of a telescope made with your own hands at home.

Up to ten thousand rubles. This device will certainly be more suitable for high-quality observation of the night sky. The mechanical part of the body and equipment will be quite poor, and you may have to spend money on some spare parts: eyepieces, filters, etc.

From twenty to one hundred thousand rubles. This category includes professional and semi-professional telescopes. Surely a beginner will have no need for a mirror camera with an astronomical cost. This is simply, as they say, a waste of money.

Conclusion

As a result, we got acquainted with important information about how to make a simple telescope with your own hands, and some of the nuances of buying a new device for observing the stars. In addition to the method that we have considered, there are others, but this is a topic for another article. Whether you've built a telescope at home or purchased a new one, astronomy will take you into the unknown and provide experiences you've never experienced before.

The telescope is designed so that a person, looking through it, sees objects from a greater viewing angle than he sees them with the naked eye.

An increase in the angle of view is achieved by combining a biconvex glass with a biconcave glass or two biconvex glasses. These glasses are also called lenses and lentils.

A biconvex lens, as its name suggests, is convex on both sides and is thicker in the middle than at the edges. If such a lens is turned towards a distant object, then by placing a sheet of white paper behind the lens at a certain distance, you will notice that it produces an image of the object to which the lens is turned. This is especially noticeable if you turn the lens towards the Sun - on a white sheet you get an image of the Sun in the form of a bright circle, and you can see that the light rays, having passed through the lens, are collected by it. If you hold the paper in this position for some time, it can be burned - so much radiant energy is collected here.)

The point through which any ray passes without refraction is called the optical center of the lens (for a biconvex lens, the optical center coincides with the geometric one).

The center of the sphere of which the lens surface is a part is called the center of curvature. In a symmetrical biconvex lens, both centers of curvature lie at equal distances from the optical center. All straight lines passing through the optical center of the lens are called optical axes. The straight line connecting the center of curvature to the optical center is called the main optical axis of the lens.

The point where the rays passing through the lens are collected is called the focus.

The distance from the optical center of the lens to the plane in which the focus is located (the so-called focal plane) is called the focal length. It is measured in linear measures.

The focal length of the same lens varies depending on how far away from the lens itself the object to which it is facing is located. There is a certain law that the focal length depends on the distance to the object. For calculating spotting scopes, the most important thing is the main focal length, i.e. the distance from the optical center of the lens to the main focus. The main focus is the point at which, after refraction, a beam of rays parallel to the main optical axis converges. It lies on the main optical axis, between the optical center and the center of curvature. The image of an object is obtained at the main focal length, or, as they also say, “at the main focus” (which is not entirely accurate, because the focus is a point, and the image of an object is a flat figure), when the object is so far from the lens that the rays coming from it, fall onto the lens in a parallel beam.

The same lens always has the same principal focal length. Different lenses, depending on their convexity, have different principal focal lengths. Biconvex lenses are often called “converging” lenses.

The converging power of each lens is measured by its principal focal length. Often, when talking about the collecting property of a biconvex lens, instead of the words “principal focal length” they simply say “focal length”.

The more a lens refracts rays, the shorter its focal length. To compare different lenses, you can calculate the ratio of their focal lengths. If, for example, one lens has a main focal length of 50 cm, and the other 75 cm, then, obviously, the lens with a main focal length of 50 cm refracts more strongly. We can say that its refractive properties are greater than those of a lens with a focal length of 75 cm , as many times as 75 cm is greater than 50 cm, i.e. 75/50 = 1.5%

The refractive property of a lens can also be characterized by its optical power. Since the refractive property of a lens is greater, the shorter its focal length, the value 1: F can be taken as a measure of optical power (F is the main focal length). The unit of optical power of a lens is the optical power of such a lens, the main focal length of which is 1 m. This unit is called diopter. Therefore, the optical power of any lens can be found by dividing 1m by the principal focal length (F) of that lens, expressed in meters.

Optical power is usually denoted by the letter D. The optical powers of the above lenses (one F1 = 75 cm, the other F2 = 50 cm) will be

D1= 100cm / 75cm = 1.33

D2= 100cm / 50cm = 2

If you buy a 4-diopter lens in a store (this is how glasses for glasses are usually designated), then its main focal length is obviously equal to: F = 100 cm / 4 = 25 cm.

Usually, when denoting the optical power of a converging lens, a “+” (plus) sign is placed in front of the number of diopters.

A biconcave lens has the property of scattering rather than collecting rays. If you turn such a lens towards the Sun, then no image is obtained behind the lens; the rays falling on the lens in a parallel beam come out of it in a diverging beam in different directions. If you look at an object through such a lens, the image of this object appears reduced. The point where the extensions of the rays scattered by the lens “converge” is also called the focus, but this focus will be imaginary.

The characteristics of a biconcave lens are determined in the same way as a biconvex lens, but they are related to the apparent focus. When designating the optical power of a biconcave lens, put a “-” (minus) sign in front of the number of diopters. Let us write down in the summary table the main characteristics of biconvex and biconcave lenses.

When constructing optical instruments, a system of two or more lenses is often used. If these lenses are attached one to the other, then the optical power of such a system can be calculated in advance. The required optical power will be equal to the sum of the optical powers of the constituent lenses or, as they also say, the diopter of the system is equal to the sum of the diopters of the lenses that make it up:

This formula makes it possible not only to calculate the optical power of several folded glasses, but also to determine the unknown optical power of a lens if there is another lens with a known power.

Using this formula, you can find out the optical power of a biconcave lens.

Let, for example, we have a diverging lens and want to determine its optical power. We apply a collecting lens to it so that this system produces a real image. If, for example, by applying a converging lens of +3 diopters to a diverging lens, we received an image of the Sun at a distance of 75 cm, then the optical power of the system is equal to:

D0=100cm / 75cm = +1.33

Since the optical power of the converging lens is +3 diopters, the optical power of the diverging lens is -1.66

The minus sign precisely shows that the lens is diverging.

A change in the distance from the object to the lens also entails a change in the distance from the lens to the image, i.e., the focal length of the image. To calculate the focal length of an image, use the formula below.

If d is the distance from the object to the lens (more precisely, to its optical center), f is the focal length of the image and F is the main focal length, then: 1/d + 1/f = 1/F

From this formula it follows that if the distance of the object from the lens is very large, then practically 1/d=0 and f=F. If d decreases, then f must increase, that is, the focal length of the image given by the lens increases, and the image moves further and further from the optical center of the lens. The value of F (principal focal length) depends on the refractive index, the glass from which the lens is made, and the degree of curvature of the lens surfaces. The formula expressing this dependence is:

F=(n-1)(1/R1+1/R2)

In this formula, n is the refractive index of glass, R1 and R2 are the radii of those spherical surfaces by which the lens is limited, i.e., the radii of curvature. It is useful to keep these dependencies in mind so that even with a superficial examination of the lens, you can judge whether it is long-focus (the surfaces are slightly curved) or short-focus (the surfaces are very noticeably curved).

The properties of converging and diverging lenses are used in spotting scopes.

The telescope device shows the optical design of a Galilean telescope. The tube consists of two lenses: a biconvex lens, facing the object, and a biconcave lens, through which the observer looks.

The lens that collects rays from the observed object is called an objective lens, the lens through which these rays exit the tube and enter the eye of the observer is called an eyepiece.

A distant object (not shown in the telescope drawing) is located far to the left; rays fall on the lens from its upper point (A) and from its lower point (B). From the optical center of the lens, the object is visible at an angle AO B.

Having passed through the lens, the rays should have been collected, but biconcave glass, placed between the lens and its main focus, seems to “intercept” these rays and scatter them. As a result, the observer's eye sees the object as if the rays from it are coming at a large angle.

The angle at which an object is visible to the naked eye is AOB, and to an observer looking through the pipe, it seems that the object is at ab and is visible at an angle that is greater than the angle AOB. The ratio of the angle at which an object is visible through the telescope to the angle at which the object is visible to the naked eye is called the magnification of the telescope. Magnification can be calculated if the principal focal length of the objective F1 and the principal focal length of the eyepiece F2 are known. Theory shows that the magnification W of a Galilean tube is equal to: W= -F1/F2= -D2/D1, where D1 and D2 are the optical powers of the lens and eyepiece, respectively.

The minus sign indicates that in a Galilean tube the optical power of the eyepiece is negative.

The length of the Galilean tube should be equal to the difference between the focal lengths of the objective F1 and the eyepiece F2.

Since the position of the focus changes depending on the distance to the observed object, when viewing nearby terrestrial objects, the distance between the lens and the eyepiece should be greater than when viewing celestial bodies. To be able to properly install the eyepiece, it is inserted into the retractable tube.

The design of a spyglass shows the optical design of a Keplerian spyglass. The object is far to the left and is visible at an angle AOB. The rays from the top and bottom points of the object are collected at O" and O" and, going further, are refracted by the eyepiece. By placing the eye behind the eyepiece, the observer will see an image of the object at an angle A "NE". In this case, the image of the object will appear upside down.

Keplerian tube magnification: W= F1/F2= D2/D1,

The distance between the objective and the eyepiece in a Keplerian tube is equal to the sum of the focal lengths of the objective F1 and eyepiece F2. Consequently, the Keplerian tube is always longer than the Galilean tube, which gives the same magnification at the same focal length of the lens. However, this difference in lengths decreases the greater the magnification.

In the Keplerian tube, as in the Galilean one, the movement of the eyepiece tube is provided for the possibility of observing objects located at different distances.