How to make a telescope from a magnifying glass. How to make a high-quality and powerful telescope yourself from ordinary spectacle lenses with your own hands. Rules for selecting lenses for glasses when making a telescope at home. What makes a powerful telescope different?

This article is intended for those amateur astronomers who have already played with binoculars and a refracting telescope, looked at the phases of Venus, the rings of Saturn and the moons of Jupiter, and want something less boring and more stunning. For example, 1000x with a huge lens. It is impossible to do this with lenses alone: ​​they produce so-called chromatic aberration, which manifests itself in the form of rainbow halos around objects, the stronger the stronger the magnification of the telescope.

Therefore, the task arises of assembling a homemade reflecting telescope, that is, a telescope on mirrors. In its simplest form, it consists of two mirrors (objective and diagonal) and one eyepiece lens.

Where to get it

The main mirror-lens of a reflecting telescope is its most important and critical part. And it is also the most difficult to manufacture. Finding a ready-made mirror of this type is almost impossible.

Although there is one way: you can make this from a concave or convex-concave lens. Find the largest concave or convex-concave lens you can find. It is important that the focal length be as high as possible, and, therefore, the concavity as small as possible: from too powerful concave lenses, not a spherical, but a parabolic shape is required, and this is a completely different deficiency that cannot be improvised in any way.

The most reliable calculation is to find a plano-concave one with a diameter of 10-12 cm and an optical power of 1 diopter. Look for it in optical stores. Homemade telescope Thus, it will not work 1000 times, but something can be done with this.

Silver plating using chemistry

Then you need to do silvering to get a mirror. Prepare a solution called Tollens' reagent. In order to prepare this reagent, you need: silver nitrate (lapis), caustic soda (caustic soda) and ammonia solution.

This reagent kit also includes formaldehyde (formaldehyde solution). Dissolve 1 g of silver nitrate in 10 ml of water, and 1 g of sodium hydroxide in another 10 ml of water. Mix these solutions, a white precipitate should form. Add ammonia solution until the precipitate dissolves. This solution is Tollens' reagent.

To use it for silvering, you should pour it into the concave part, which has previously been thoroughly cleaned of any contaminants. If the concavity is very weak, you should make a barrier of wax or plasticine along its edge.

Having poured the reagent, you should begin to add formaldehyde to it in frequent drops. Soon a film of silver will form and it will turn into a concave mirror. Keep in mind that Tollens' reagent does not have a long shelf life; it must be used immediately after it is prepared.

There are also ways to make a concave surface yourself, first of all - grinding the concave surface on glass circles. However, these methods are too complicated and are not recommended for use by beginners.

A diagonal mirror should be made in the same way as a concave one. It should be perfectly straight; For its manufacture, the flat side of any plano-convex or plano-concave is suitable.

Telescope assembly

Now you can start assembling your homemade one. You will need a tube exactly the length of the focal length (if you used a 1 diopter plano-concave lens for manufacturing, then take a tube 100 cm long, +0.5-1 cm adjustment for thickness).

The pipe should be open at one end and closed at the other, and painted inside with the blackest paint you can find. The diameter of the pipe should be 1.25 times the diameter of the refractor mirror; if you used a lens with a diameter of 100 mm to make it, take a pipe with a diameter of 125 mm.

Attach the lens mirror to the bottom of the pipe, exactly in the center. To make it convenient to do this, it is better to provide a removable bottom. You can attach the lens to the bottom, for example, with superglue.

Make a hole closer to the open end of the pipe. To calculate the desired position for the hole, measure its radius from the open end of the pipe. This is where the center of the hole should be. The eyepiece will be fixed in this hole (perpendicular to the pipe).

It should hang on the optical axis at an angle of 45 degrees. If the angle is maintained correctly, then when you look through the eyepiece you will see the image. If you don't succeed the first time, experiment with the angle.

Observing stars and other astronomical bodies in the sky is a very entertaining process. Planets solar system, satellites, constellations, “shooting stars” - all this is only a small part of the vast and completely unknown Universe. The most clearly visible is the Moon, the closest cosmic body to us, not counting man-made artificial satellites of the Earth. However, even the Moon is quite difficult to see in detail with the naked eye. For this purpose, mankind has invented a special device - a telescope, which allows you to “bring closer” the observed object and study it in more detail. Let's try to figure out how to make a simple telescope with your own hands.

All optical telescopes can be divided into two groups: refractor telescopes, which use lenses that refract and thereby collect light, and reflecting telescopes, which use mirrors as such an element. It is easier to make a refracting telescope with your own hands, since this requires collecting lenses, which are not difficult to find, unlike special collecting mirrors. We will make such a telescope with 50x magnification, for which we will need: thick paper (Whatman paper), cardboard, black paint, glue and two collecting lenses.

First, let's look at the structure of a simple refracting telescope. Its main part is the lens - a biconvex lens located in the front of the telescope and collecting radiation. Its main characteristics are: lens diameter (aperture) , the larger the aperture, the more radiation the telescope collects, that is, the greater its resolution, and, as a result, higher magnifications can be used; lens focal length. Other an important part telescope - eyepiece. The magnification of a telescope is calculated as a value equal to the ratio of the focal length of the lens to the focal length of the eyepiece ¸ and is expressed in multiples:

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In addition, there is such a thing as maximum useful increase telescope, which is equal to twice the diameter of the lens , expressed in millimeters. It makes no sense to make a telescope with higher magnification, since most likely it will not be possible to see new details, and the overall brightness of the image will significantly decrease. Thus, if you need to make a telescope with 50x magnification, then the lens diameter must be at least 25 mm. But a small diameter reduces resolution, so for a 50x telescope it is advisable to use a lens with a diameter of 60 mm.

The minimum useful magnification of a telescope is determined by the diameter of its eyepiece , which should not exceed the diameter of the fully opened pupil of the observer’s eye, otherwise not all of the light collected by the telescope will enter the eye and will be lost. The maximum pupil diameter of the observer's eye is usually 5-7 mm, so the minimum usable magnification is 10x (aperture times 0.15).

We proceed directly to the manufacture of the telescope. Make a telescope from whatman paper large sizes will not work, since whatman paper does not have sufficient rigidity, which will lead to problems with adjusting the telescope. Optimal size is approximately 1m. Therefore, the focal length of the lens should also be about 1 m, which corresponds to an optical power of +1 diopter. For the lens, you need to make a pipe from whatman paper with a length of 60-65 cm and a diameter corresponding to the diameter of the objective lens (6 cm). Inner part The pipes should be painted black before gluing to prevent excess radiation from entering the eyepiece. The lens can be secured in the lens tube using two toothed rims cut out of cardboard.

For the eyepiece, you need to make a tube 50-55 cm long. The lens and eyepiece tubes are also connected to each other using cardboard rims, which allow the eyepiece tube to move relative to the lens tube using little force. To provide a telescope with 50x magnification, the eyepiece lens must have a focal length of 2-3 cm.

The resulting telescope has one drawback - it gives an inverted image. To correct this, you will need another converging lens that has the same focal length as the eyepiece lens. An additional lens must be installed in the eyepiece tube.

When making a telescope, it should also be taken into account that in telescopes with high magnification, various diffraction phenomena are more pronounced, which significantly impairs visibility. This magnification is commonly used to observe features on the disks of planets and the Moon, as well as when observing double stars. Therefore, to reduce this effect, you need a diaphragm (a black plate with a hole 2–3 cm in diameter), which is placed in the place where the rays from the lens converge in focus. After this improvement, the image will become less bright, but clearer.

Using the proposed method, we suggest you solve the problem:

What should be the main parameters of a telescope with 100x magnification?

Do you suddenly want to make a telescope with your own hands? Nothing strange. Yes, nowadays it is not difficult to buy almost any optical device, and not so expensive. But sometimes a person is attacked by a thirst for creativity: he wants to figure out what laws of nature the principle of operation of a device is based on, he wants to design such a device from start to finish and experience the joy of creativity.

DIY spyglass

So, you get down to business. First of all, you will learn that the simplest telescope consists of two biconvex lenses - the objective and the eyepiece, and that the magnification spyglass obtained by the formula K = F / f (the ratio of the focal lengths of the lens (F) and eyepiece (f)).

Armed with this knowledge, you go digging through boxes of various junk, in the attic, garage, shed, etc. with a clearly defined goal - to find more different lenses. These can be glasses from glasses (preferably round ones), watch magnifiers, lenses from old cameras, etc. Having collected a supply of lenses, start measuring. You need to choose a lens with a larger focal length F and an eyepiece with a smaller focal length f.

Measuring focal length is very simple. The lens is directed at some light source (a light bulb in the room, a lantern on the street, the sun in the sky or just a lit window), a white screen is placed behind the lens (a sheet of paper is possible, but cardboard is better) and moves relative to the lens until It will not produce a sharp image of the observed light source (inverted and reduced).

After this, all that remains is to measure the distance from the lens to the screen with a ruler. This is the focal length. You are unlikely to cope with the described measurement procedure alone - you will need a third hand. You'll have to call an assistant for help.

Once you have selected your lens and eyepiece, you begin constructing the optical system to magnify the image. You take the lens in one hand, the eyepiece in the other, and through both lenses you look at some distant object (not the sun - you can easily be left without an eye!). By mutually moving the lens and eyepiece (trying to keep their axes on the same line), you achieve a clear image.

The resulting image will be enlarged, but still upside down. What you are now holding in your hands, trying to maintain the achieved relative position of the lenses, is the desired optical system. All that remains is to fix this system, for example, by placing it inside a pipe. This will be the spyglass.

But don't rush into assembly. Having made a telescope, you will not be satisfied with the image “upside down”. This problem is solved simply by a wrapping system obtained by adding one or two lenses identical to the eyepiece.

You can obtain a wraparound system with one coaxial additional lens by placing it at a distance of approximately 2f from the eyepiece (the distance is determined by selection).

It is interesting to note that with this version of the reversing system, it is possible to obtain greater magnification by smoothly moving the additional lens away from the eyepiece. However, you won’t be able to get a strong magnification if you don’t have a very high-quality lens (for example, glass from glasses). The phenomenon of so-called “chromatic aberration” interferes, when the image is painted in rainbow shades.

This problem is solved in “purchased” optics by composing a lens from several lenses with different refractive indices. But you don’t care about these details: your task is to understand the circuit diagram of the device and build the simplest working model according to this scheme (without spending a penny).

You can obtain a wraparound system with two coaxial additional lenses by positioning them so that the eyepiece and these two lenses are spaced from each other at equal distances f.

Now you have an idea of ​​the telescope design and know the focal lengths of the lenses, so proceed to assembly optical device. The simplest thing is to twist pipes (tubes) from sheets of whatman paper, securing them with rubber bands “for money”, and fix the lenses inside the tubes with plasticine. The inside of the pipes must be painted with matte black paint to prevent external exposure.

The result seems to be something primitive, but as a zero option it is very convenient: it’s easy to remake, change something. When this zero option exists, it can be improved for as long as desired (at least replace the Whatman paper with more decent material).

Let's try to make a telescope. In order to make a simple but fully functional telescope yourself, you need whatman paper, black ink, office glue or paste and two optical lenses. We present telescope options with magnifications of thirty, fifty and one hundred times. They differ only in extended length and objective lenses.

To begin with, it is best to make a telescope with a magnification of 50 times.
From a suitable sheet of whatman paper, roll up a tube 60 - 65 cm long. The diameter should be slightly larger than the diameter of the objective lens - about 6 cm if you are using a standard spectacle lens. Unfold the sheet and ink ink the part of the sheet that will become the inner surface of the telescope.

Otherwise, rays that enter the tube from a source other than the object of observation will be reflected many times and enter the eyepiece lens and veil the image.
After inner surface blackened, you can roll and glue the pipe. Attach an objective lens of +1 diopter (you will find it in the Optics store) to the end of the pipe as shown in the figure - using two cardboard rims with paper teeth.

The second tube with eyepiece lens 2 should move with little effort, but quite freely, in the first one.
You will most likely find the lens for the eyepiece in the photographic goods department or remove it from a binocular that is “permanently” broken. The lens should be selected as follows: direct light at it from a distant source, for example Sunbeam, and watch where they come into focus. The distance from the lens to the focus is called the focal length of that lens (f). For our purposes, the eyepiece should have f=3-4 cm. As a rule, such lenses have a small diameter, therefore the eyepiece lens mount is somewhat different from the lens mount.

Roll a cardboard tube 6 - 7 cm long with such a diameter that the lens you selected fits tightly into it. If it is equipped with a wide metal rim, it does not fall out of the tube and does not require additional fastening at the edges.
The tube with lens 2 is secured inside the much wider tube of the telescope using two cardboard circles with holes in the middle and teeth made of less dense paper.

30 mm. The same, plus Jupiter's moons Europa, Io, Callisto and Ganymede. In a very fortunate coincidence - Saturn's satellite Titan. Stripes on the disk of Jupiter. Planet Neptune - in the form of a star.

40 mm. The double star Castor - Alpha Gemini separates. The Great Orion Nebula and open star clusters in the constellations Perseus, Auriga, and Canis Major and Cancer.

80 mm. Shadows from Jupiter's satellites are visible as they pass in front of the planet's disk. The ring nebula M57 has a dark hole at its center. Several satellites of Saturn. The Cassini gap in the rings of Saturn.

100 mm. The satellite of Rigel - Alpha Orionis - and the North Star - Alpha Ursa Minor are visible.

120 mm. Saturn's moon Enceladus. Details on the disk of Mars during oppositions are seas and polar caps made of carbon dioxide.

150 mm. Duality of Epsilon Bootes. Division of the globular cluster M13 into individual stars.

200 mm. The Encke division in the ring of Saturn is several concentric rings separated by spaces. Spirals in the Andromeda Nebula.

250 mm. Pluto. Satellites of Uranus.
300 or more. Horsehead Nebula. Satellite of Sirius. Galaxies in detail. The central star in the ring nebula M57. Ball star cluster in the M31 galaxy.

And so we summarize - in order to build a simple refracting telescope, you need only two collecting lenses - a long focal length (low optical power) for the objective and a short focal length (strong magnifying glass) for the eyepiece.

You should look for them at flea and radio markets, in stores spectacle optics at worst.
The first lens - the lens of a telescope, if you point it without anything else at some distant object, will create an inverted image of it behind itself, at a distance approximately equal to its focal length. This image can be seen on frosted glass or paper or, without any glass, by simply standing behind the lens at a distance greater than the focal length and looking in the direction of the lens.

Please note that in the latter case the eye will have to accommodate not “to infinity,” as when considering the horizon line, but as when considering a certain material object located from the eye at the same distance as the image plane. You will see a magnified inverted image of a distant object, with the magnification factor being equal to the focal length of the lens in cm divided by 25 - distance best vision human eye. If the focal length of the lens is less than 25 cm, the image will be reduced. The simplest telescope is basically ready!
Now we will improve it. First from the optical side. In order to obtain high magnification with a small focal length of the lens, an eyepiece or magnifying glass is used. The image obtained by the first lens - the objective - is viewed not with the naked eye from the distance of best vision, but through the eyepiece from a shorter distance, approximately equal to the focal length of the eyepiece. In this case, the magnification of the telescope will be equal to the ratio of the focal lengths of the lens and eyepiece..
Now from the mechanical side. In order not to hold all this equipment in your hands, we take two tubes, one of which slides into the other, or we make them out of paper and PVA, blackening them from the inside activated carbon or a battery filled with PVA (a can of matte black paint is also suitable), and attach a lens to the end of one tube and an eyepiece to the end of the other. After this, we slide one tube into the other so that we can see a clear image of the distant objects. The pipe is ready!!!
Essential points: lens - spectacle glass, condenser lens or achromatic gluing with a focal length of 40 - 100 cm. The diameter of the telescope entrance aperture is 20 - 30 mm, if the gluing is (a lens from some kind of optical device), then more is possible. If the diameter is larger than the given values, the image may turn out to be low-contrast. To limit the diameter, we make an aperture - we cut out a cardboard circle with a diameter equal to the outer diameter of the lens, and in the center we cut out a round hole with a diameter of 20 - 30 mm. We place the aperture close to the lens in front or behind it.
The magnification of such a telescope is 20 - 50 times.

The objective and eyepiece lenses should be installed into the tube as coaxially as possible. The lens must be glass. What is visible: at 28 mm 40 times outside the city, stars up to the 9th magnitude, the ring of Saturn and the gap between it and the disk, satellites and two dark stripes on Jupiter (they appear rather orange), the phase of Mars when it was 6 seconds in diameter, craters on the Moon, spots on the Sun (only when projected with an eyepiece, do not look with the eye!!!).

The conclusion is this: in terms of detail visibility, this product, if assembled well, will surpass 8x binoculars.

Just in case, we remind you that a +1 diopter spectacle lens has a focal length of 1 meter and it is quite sufficient for such a simple telescope. You should not follow popular recommendations and make a lens from a pair of identical lenses +0.5 diopters (concave to each other). This is a “Periscope” scheme, which has some advantages only in fields of 30-50 degrees, which is not relevant for telescopes with their fields of half a degree.

The telescope is unfairly considered a difficult device to use and manufacture. This is a normal attitude towards devices that seem incomprehensible. But we assure you that it is possible to do it yourself. Even in a couple of hours.

We will make a telescope with magnification from 30 to 100 times. There are only three telescopes in this range, and they are the same, except for the differences in lenses and tube length.

Required:

1. Whatman.
2. Glue.
3. Paint or ink.
4. Optical lens 2 pcs.

The easiest telescope for beginners with 50x magnification. Let's start with it.

Making a lens

We roll whatman paper into a 65 centimeter pipe. The diameter of the pipe should be slightly larger than the objective lens. If the lens is spectacle, the diameter of the pipe will not exceed six centimeters. Inner side Paint the sheet black.

Now the sheet should be secured with glue. We attach the lens inside the pipe using jagged cardboard, as shown below.

1. Lens from the lens.
2. Eyepiece lens.
3. Fastening.
4. Lens tube mount.
5. Add. lens.
6. Diaphragm.

Making an eyepiece

A lens from a binocular will be suitable for the eyepiece. Focal length will not exceed 4 centimeters. You can check this in a simple way. Place the lens under an external light source (even the Sun) and project the light onto the sheet. You need to make such a distance that the rays passing through the lens are collected at a small point, this will be the focal length.

Roll the sheet into a paper tube so that the lens fits tightly into it. This tube is then secured to a larger diameter pipe using jagged cardboard circles.

That's it, the telescope is ready. It has one drawback - objects in it will be reflected upside down. To avoid this, you need to add another four-centimeter lens to the eyepiece tube.

A telescope with thirty-fold magnification is made in the same way, at the same time a lens of a couple of diopters is added and the length is increased to seventy centimeters.

100x magnification differs from the thirty-fold lens only in that the lens is two half diopters larger and two meters long. Through such a telescope you will see the Moon in full view, and Mars and Venus will appear the size of a pea.

This length and small lens size may cause rainbow coloring, which you can remove with aperture, installed at the focal point. This will reduce the brightness of the image, but there will be no rainbow coloring, called diffraction.

Remember that a two-meter telescope under the weight of the lenses can bend, that is, he needs wooden supports.

So you've created a telescope that will ignite anyone's love of astronomy.