How to make a telescope from a spyglass. How to make a telescope at home. How to assemble a telescope at home - lens manufacturing procedure
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 spoiled eye"" from 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 can be pasted over inner surface pipes with black (painted) paper.
It is advisable that internal cavity The spyglass was sealed, then the pipe would 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- from optical instruments: film cameras, microscopes, binoculars, photo enlargers, overhead 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.
Everyone probably knows that the most important instrument, the main tool of an astronomer, is the telescope. But what is the main advantage of a telescope over the naked eye? Not everyone knows this.
It is commonly believed that the main property of a telescope is to magnify images of celestial bodies. When approaching a telescope, schoolchildren usually ask: “How many times does it magnify?” In fact, the power of a telescope is determined not by the magnification it provides, but by the diameter of the lens. After all, the larger the diameter of the lens, the larger its area, and therefore the greater the amount of light that the lens collects. Even a school telescope with a lens diameter of only 80 mm collects about 250 times more light than the eye. This is understandable: the diameter of the pupil (5 mm) is 16 times smaller than the diameter of the school telescope, and 162 = 25. Therefore, through a school telescope we will see stars that are 250 times fainter than those visible to the naked eye. It must be remembered that stars, even in the most powerful telescope, appear to be luminous points, therefore the term “magnification” is not applicable to their observations.
Another thing is the Sun, Moon, planets, nebulae and other so-called extended celestial bodies. Thanks to the combination of optical system Using a telescope lens and a special complex magnifying glass - an eyepiece, you can obtain enlarged images of these luminaries. Let's see how this happens.
A telescope lens is a system of lenses whose task is to construct a real image of the luminary. This image, obtained at the main focus of the lens, can be taken on the screen, photographed by placing a photographic plate here, or viewed through an eyepiece. The distance from the lens or eyepiece to the main focus is called the focal length. The eyepiece has its own focal length, usually many times smaller than the lens. The magnification of a telescope is equal to the ratio of the focal lengths of the lens and eyepiece.
It would seem that one should achieve the greatest possible magnification of the telescope in order to examine the smallest details on the Moon, Mars and other planets. In fact, the ability to examine certain small details (the resolving power of the telescope) is again determined not by magnification. and the diameter of the lens. To find out what the smallest details can be discerned in a given telescope, you need to divide 120 by the diameter of the lens, expressed in millimeters. We will obtain the apparent dimensions of the smallest discernible features in arcseconds. Let us recall that 1" arc is 1/3600°. This is the angle at which the thickness of an ordinary match is visible from a distance of 400 m. At the distance of the Moon, 1" arc corresponds to the linear size of the part of 2 km, at the distance of Mars (during the period of great opposition) - 300 km. Such details can be discerned in a telescope with a lens of 120 mm or more.
Of course, higher magnifications allow you to better see the fine details of the surface of the Moon or planets. But they also have negative sides. At high magnifications, the image becomes paler and less clear, as the amount of light collected by the lens is distributed over a larger area of the image. In addition, at high magnifications, image jitter caused by atmospheric fluctuations, as well as distortions associated with imperfections in the telescope optics (aberrations), increase accordingly. Therefore, it is better to choose not the highest magnification, but one at which the light can be seen most clearly through the telescope.
There are telescopes various types. An amateur astronomer usually has to deal with two of them: a refractor and a reflector. A refractor - "refracting" - is the oldest type of telescope. Its lens consists of lenses that refract the rays falling on them.
In the USSR, two types of refracting telescopes are produced for schools. Large model (see picture) with an objective lens diameter of 80 mm, a focal length of 800 mm and three eyepieces giving magnification of 28, 40 and 80 times. The telescope is mounted on a so-called equatorial installation, which allows you to monitor the star long time, rotating the telescope around only one axis - the polar one (directed towards the North Star). The inclination of the polar axis to the horizon must be equal to the geographic latitude of the place, which is determined from the map. The declination axis runs perpendicular to the polar axis. Rotating the tube around both axes, we point the telescope at the luminary, secure it with clamping screws and, watching the luminary through the eyepiece, slowly turn the telescope around the polar axis using a micrometer key.
Scheme homemade telescope-refractor made from spectacle glasses:
1 - main tube, 2 - eyepiece tube, 3 - lens, A - lens frame, 5 - eyepiece, 6 - eyepiece frame, 7 - diaphragm.
A small model of a school refracting telescope (MSR) (see figure) has a lens with a diameter of 60 mm, a focal length of 600 mm. The eyepieces provide magnification of 30x and 60x. Unlike the large model, the small one has an azimuthal installation. In it, the telescope tube can rotate around two axes: vertical and horizontal. To monitor the star, the telescope has to be rotated simultaneously around both axes, which is very inconvenient (how to avoid this is described in the “Handbook for an Amateur Astronomy” by P. G. Kulikovsky, “Science”, 1961, p. 246). After all, the daily path of a star across the sky is usually located at an angle to the horizon plane, and this angle changes during the day. Both telescopes come with various additional accessories: a solar screen, a zenith prism, dark glasses and light filters, etc. Often, an astronomy enthusiast does not have the opportunity to purchase a factory telescope. In this case, we can offer two options for a homemade telescope: for beginner amateurs - a refractor made from spectacle glasses, for more experienced ones - a reflector. Manufacturing homemade refractor accessible to any student.
First of all, you need to purchase a lens and eyepiece. For the lens, you can use a simple biconvex lens of 1 diopter (its focal length is 1 m). Such lenses are available in optical stores and pharmacies. Two lenses for glasses (“meniscus”) of +0.5 diopters each, located with their convex sides outward at a distance of 30 mm from one another, replace a lens of 1 diopter. Between them you need to place a diaphragm with a hole with a diameter of about 30 mm. Attachment lenses for a camera, for example, the “Amateur” type, are also suitable. A lens of 1 diopter can be replaced by lenses of 0.75 or 1.25 diopters (their focal lengths are 133 and 80 cm). The lens must certainly be round and have a large diameter (up to 50 mm). For the eyepiece, you can take a strong magnifying glass of small diameter, an eyepiece from a microscope (including a school type), from an old theodolite, level or binoculars.
To determine what magnification our telescope will give, we measure the focal length of the eyepiece. To do this, on a clear day, point the eyepiece at the Sun and place a sheet of white paper behind it. We will zoom in and out of the sheet until we get the smallest and brightest image of the Sun (to prevent the paper from catching fire, cover the eyepiece with an illuminated film or plate). The distance between the center of the eyepiece and the image is the focal length of the eyepiece. By dividing the focal length of the lens (it is equal to 100 cm divided by the number of diopters of the spectacle lens) by the focal length of the eyepiece, we obtain the magnification of the telescope.
Typically, you can get 20-50x magnification with a homemade refractor. The telescope tube can be made from paper. Take several sheets of large format paper and a round piece of wood with a diameter 2-3 mm larger than the objective lens. Wrap the blank with paper several times until the pipe is of sufficient strength and thickness. When winding the paper, coat each layer with glue - regular office glue, casein glue, or a paste made from potato or wholemeal wheat flour. Outer surface Cover the pipes with light enamel or oil paint (you can use varnish), and black out the inside with ink to avoid harmful reflections of light from the walls of the pipe. It is better to do this before gluing the pipe. The pipe can also be made from sheet metal, duralumin and other materials. In the same way, a retractable tube of smaller diameter for the eyepiece is made. Its inner diameter depends on the outer diameter of the eyepiece frame. The main tube (1) is made ten centimeters shorter than the focal length of the lens; the length of the eyepiece tube (2) is about 40 cm. To aim the telescope at focus (“at clear vision"), the eyepiece tube should move in and out tightly, with friction. The stars in the telescope, when set to focus, appear as bright points rather than blurry disks. The objective lens (3) is inserted into the front end of the tube using a frame (4), consisting of two cardboard rings with a cut and two short paper tubes of slightly smaller diameter than the lens. With the help of these tubes, the lens is tightly clamped between the rings.
To make observation more convenient, you need to make a tripod for the telescope. The easiest way is to make a wooden azimuth tripod, on which the pipe rotates around two axes: vertical and horizontal. However, on such a tripod it is impossible to point the telescope at the sky near the zenith. This inconvenience can be eliminated. You just need to slightly change the design of the tripod. The pipe at the other end of the horizontal axis must be balanced with a load. To avoid having to support the pipe with your hand all the time, make a locking screw, or even better, two: for the vertical and horizontal axes.
With the help of the refractor you made, you will be able to observe the mountains on the Moon, the rings of Saturn, the phases of Venus, the disk of Jupiter and its 4 satellites, double stars, some star clusters - the Pleiades, the Manger. Observe sunspots by projecting an image of the Sun onto a screen - a sheet of white paper, protecting it from the direct rays of the Sun with a piece of cardboard with a hole in the middle, placed on a tube. For complex observations this tool is not sufficient.
Probably everyone in their life has been at least a little interested in astronomy and wanted to have with them an instrument that would allow them to take a closer look at the mysteries of the starry sky.
It’s good if you have binoculars or a telescope - even with such rather weak astronomical instruments you can already admire the beauty of the starry sky. But if your interest in this science is strong enough, but there is no access to the tool at all, or the available tools do not satisfy your curiosity, you will still need a more powerful tool - telescope which you can do yourself at home. In our article step-by-step instruction with photos and videos on how to make a telescope with your own hands.
A factory-made telescope will cost you quite a lot, so purchasing it is only appropriate if you want to engage in amateur or amateur astronomy. professional level. But first, in order to acquire basic knowledge and skills, and finally understand whether astronomy is really for you, you should try to make a telescope with your own hands.
In many children's encyclopedias and other scientific publications you can find a description of how to make a simple telescope. Already such a tool will allow you to see craters on the Moon, the disk of Jupiter and its 4 satellites, the disk and rings of Saturn, the crescent of Venus, some large and bright star clusters and nebulae, stars, invisible to the naked eye. It is immediately worth noting that such a telescope cannot claim image quality in comparison with factory-made telescopes due to the mismatch of the purpose of the optics that will be used.
Telescope device
First, a little theory. The telescope, as in the photo, consists of two optical units - lens And eyepiece. The lens collects light from objects; its diameter directly determines the maximum magnification of the telescope and how faint objects can be observed. The eyepiece magnifies the image formed by the lens, followed by the human eye in the optical design.
There are several types optical telescopes, two of the most common are refractor And . The reflector lens is represented by a mirror, and the refractor lens is represented by a system of lenses. At home, making a mirror for a reflector is a rather labor-intensive and precise process that not everyone can do. Unlike a reflector, inexpensive refractor lenses can be easily purchased at an optical store.
Increase telescope is equal to the ratio Fob/Fok (Fob is the focal length of the lens, Fok is the eyepiece). Our telescope will have a maximum magnification of about 50x.
To make a lens, you need to purchase a spectacle lens blank with a power of 1 diopter, which corresponds to a focal length of 1 m. Such blanks usually have a diameter of about 70 mm. Unfortunately, spectacle lenses made in the form of menisci are poorly suited for this application, but you can stop at them. If you have a long focal length biconvex lens, it is recommended to use this one.
The eyepiece can serve as an ordinary magnifying glass(magnifying glass) with a small diameter of about 30 mm. A good option there may also be an eyepiece from a microscope.
As housing you can use two tubes made of thick paper, one short - about 20 cm (eyepiece unit), the second about 1 m (the main part of the tube). The short pipe is inserted into the long one. The body can be made either from a wide sheet of whatman paper, or from a roll of wallpaper, rolled into a tube in several layers and glued with PVA glue. The number of layers is selected manually until the pipe becomes sufficiently rigid. The inner diameter of the main pipe should be equal to the diameter of the spectacle lens.
Lens ( spectacle lens) is attached in the first pipe with the convex side outward using a frame - rings with a diameter equal to the diameter of the lens and a thickness of about 10 mm. A disk is installed immediately behind the lens - diaphragm with a hole in the center with a diameter of 25 - 30 mm - this is necessary in order to reduce significant image distortions resulting from a single lens. This will reduce the amount of light collected by the lens. The lens is installed closer to the edge of the main tube.
The eyepiece is installed in the eyepiece assembly closer to its edge. To do this, you will have to make an eyepiece mount from cardboard. It will consist of a cylinder equal in diameter to the eyepiece. This cylinder will be attached to the inside of the tube with two disks with a diameter equal to the inner diameter of the eyepiece assembly with a hole equal in diameter to the eyepiece.
Focusing will be accomplished by changing the distance between the lens and the eyepiece, due to the movement of the eyepiece assembly in the main tube, and fixation will occur due to friction. It is convenient to focus on bright and large objects, such as the Moon, bright stars, and nearby buildings.
When building a telescope, it is necessary to take into account that the lens and eyepiece must be parallel to each other, and their centers must be strictly on the same line.
You can also experiment with the diameter of the aperture opening and find the optimal one. If you use a lens with optical power 0.6 diopters (focal length is 1/0.6, which is about 1.7 m) - this will increase the aperture opening and increase the magnification, but will increase the tube length to 1.7 m.
It is always worth remembering that you should not look at the sun through a telescope or any other optical device. This will instantly damage your vision.
So, you are familiar with the principle of construction simple telescope and now you can make it yourself. There are other telescope options made from spectacle lenses or telephoto lenses. Any manufacturing details, as well as other information you are interested in, can be found on websites and forums on astronomy and telescope construction. This is a very broad field, and is practiced by both complete beginners and professional astronomers.
And remember, you just have to plunge into the previously unknown world of astronomy - and if you wish, it will show you many treasures of the starry sky, teach you the techniques of observation, photographing completely different objects and much more that you didn’t even know about.
Clear skies to you!
Video: how to make a telescope with your own hands
Telescope- the dream of many, because there are so many stars in the universe that you want to look at each one. Store prices for this device are a bit steep for ordinary people, so there is an option to make a telescope with your own hands.
How to make a telescope at home?
For the simplest telescope we need:
Lenses, 2 pcs.;
- thick paper, several sheets;
- glue;
- magnifying glass.
Telescope diagram.
There are two types of telescopes - refractors and reflectors. We will make a refracting telescope, since lenses for it can be bought at any pharmacy. A spectacle lens is required, diameter - 5 cm, diopters +0.5-1. For the eyepiece we will take a magnifying glass with a focal length of 2 cm.
Let's get started!
How to make the main tube for a telescope with your own hands?
From a sheet of thick paper, make a pipe, approximately 5 cm in diameter. Then, straighten the sheet and paint over it inner side in black. You can use gouache paints. Rewind into a tube and secure the position using glue.
The length of our pipe should be about 2 meters.
How to make an eyepiece tube for a telescope?
We make this pipe in the same way as the main one. Length - 20 cm. Don't forget, this pipe will be put on the main one, so the diameter should be a little larger.
Once you glue the two pipes together, all that remains is to insert the lenses. Install them as shown in the diagram. Fix them well so that they are not damaged during use.
VIDEO. How to make a telescope?
Many people, looking up at the starry sky, admire the alluring mystery of outer space. I want to look into the endless expanses of the universe. See craters on the moon. Rings of Saturn. Many nebulae and constellations. So today I will tell you how to make a telescope at home.
First, you need to decide how much magnification is required. The fact is that the larger this value, the longer the telescope itself will be. At 50x magnification the length will be 1 meter, and at 100x magnification it will be 2 meters. That is, the length of the telescope will be directly proportional to the magnification.
Let's say it will be a 50x telescope. Next, you need to purchase two lenses at any optics store (or on the market). One for the eyepiece (+2)-(+5) dioptres. The second is for the lens (+1) diopter (for a 100x telescope, (+0.5) diopter is required).
Then, taking into account the diameters of the lenses, it is necessary to make a pipe, or rather two pipes - one should fit tightly into the other. Moreover, the length of the resulting structure (in the extended state) should be equal to the focal length of the lens. In our case, 1 meter (for a lens (+1) diopter).
How to make pipes? To do this, you need to wrap several layers of paper on a frame of the appropriate diameter, coating them with epoxy resin (you can use other glue, but the last layers are better strengthened with epoxy). You can use the remnants of wallpaper that are lying around idle after renovating your apartment. You can experiment with fiberglass, then it will be a more serious design.
Next, we build the objective lens (+1) diopter into the outer tube, and (+3) diopter into the inner eyepiece. How to do it? Your imagination is the main thing to ensure precise parallelism and alignment of the lenses. In this case, it is necessary to ensure that the distance between the lenses when moving the pipes apart is within the focal length of the objective lens, in our case it is 1 meter. In the future, by changing this parameter, we will adjust the sharpness of our image.
For convenient use of the telescope, a tripod is needed to clearly fix it. At high magnification, the slightest trembling of the tube leads to blurring of the image.
If you have any lenses, you can find out their focal length in the following way: focus sunlight onto a flat surface until you get the smallest point possible. The distance between the lens and the surface is the focal length.
So, to achieve a telescope magnification of 50 times, it is necessary to place a lens of (+1) diopter at a distance of 1 meter from the lens of (+3) diopter.
For 100x magnification, we use lenses (+0.5) and (+3) changing the distance between them by 2 meters.
And this video shows the process of creating a similar telescope:
Enjoy your astronomical viewing!
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