Homemade telescope
How to make a telescope with their own hands The country of the Soviets has already considered the example of a telescope-refractor. And today we will consider how to create self-made telescope-reflector.
As you probably already know, in telescopes-reflectors the lens is represented by a mirror. To make a self-made telescope-reflectoris quite difficult, especially if you manually make mirrors for it, but the undoubted advantage of a self-made telescope-reflector in front of the same homemade refractor telescope is its greater magnification than the refractor.
Self-made telescopes-reflectors, amateur astronomers build, mainly on the Newton system. It was Isaac Newton in about 1670 that first created the telescope-reflector. This allowed him to get rid of chromatic aberrations (they lead to a decrease in the sharpness of the image, to the appearance of colored contours or bands on it, which are not on the real subject), the main defect of the then existing refractor telescopes.
The scheme of the "Newtonian" reflector looks like this:
In this scheme, the mirror 1 is the lens, alsocalled the main mirror. This mirror is parabolic or spherical. Mirror 2 is called a diagonal mirror - this mirror directs a beam of reflected rays through the eyepiece to the observer. The element indicated by the numeral 3 is the ocular unit.
The focus of the main mirror and the focus of the eyepiece inserted into the ocular tube must coincide. The focus of the main mirror is defined as the vertex of the cone reflected by the mirror rays.
The diagonal mirror is made in small dimensions, it is flat and can have a rectangular or elliptical shape. A diagonal mirror is mounted on the optical axis of the main mirror (lens), at an angle of 45 ° to it.
A conventional household flat mirror is not always suitable for use as a diagonal mirror in a home-made telescope - the telescope needs an optically more accurate surface. therefore as a diagonal mirror, you can use a flat surface of a flat-concave or flat-curved optical lens, if you first cover this plane with a layer of silver or aluminum.
Dimensions of a flat diagonal mirror for a home-made telescope are determined from the graphical construction of the cone of rays, which are reflected by the main mirror. With a rectangular or elliptical shape of the mirror, the sides or axes are related to each other as 1: 1.4.
The lens and the eyepiece of the self-made telescope-reflector are mounted in the telescope tube mutually perpendicular. To mount the main mirror of a home-made telescope, a frame, wooden or metal, is required.
To make a wooden frame for the main mirror of a homemade reflector telescope You can take a round or octagon platethickness not less than 10 mm and 15-20 mm more than the diameter of the main mirror. The main mirror is fixed on this board with 4 pieces of thick-walled rubber tube, put on the screws. For a better fixation under the heads of screws, you can put plastic washers (the mirror can not be clamped by them).
Trumpet of a home-made telescope is made of a piece of metal pipe, from several layers of cardboard glued together. You can also make a metal-cardboard tube.
Three layers of cardboard should be glued betweena joinery or casein glue, then insert the cardboard tube into the mettalic rings of stiffness. Of metal also make a bowl for the rim of the main mirror of the home-made telescope and the cover of the pipe.
The length of the tube (tube) of the home-made telescope-reflector should be equal to the focal length of the main mirror, and the inner diameter of the tube - 1.25 of the diameter of the main mirror. From the inside, the tube of the homemade telescope-reflector should be "blackened", i.e. cover with a matte black paper or paint with a black matte paint.
The eyepiece of a home-made telescope-reflector in the simplest execution can be based,as they say, "on the friction": the movable inner tube moves along the fixed external, providing the necessary focusing. The ocular unit may also be threaded.
The homemade reflector telescope must be mounted on a special support - mount before use. You can purchase as a ready-made factorymount, and make it yourself, from improvised materials. You can read more about the types of mountings for self-made telescopes in our following materials.
The country of advice reminds you that looking at the Sun without using special sun filters is extremely dangerous for the health of your eyes!
