What is a Good Telescope

Introduction on what is a good telescope:
Telescope is an optical instrument, which is used to see distant objects like stars, planets, asteroids, comets etc.

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Two types of good telescope:


There are two types of telescopes:

1) refracting type telescope

2) reflecting type telescope.


Explanation of two types of good telescope:

1) Refracting type telescope: In a good refracting type telescopes, there are two parts— one is called objective, which receives the light form the distant objects, and the other is eyepiece, which works as a magnifier to observe the real image formed by objective lens. The image formed by the objective lens can be viewed by eyepiece.

There are two types of refracting type telescopes.

i) Astronomical telescope

ii) Terrestrial telescope.

i) Astronomical telescope: The astronomical telescope includes two lenses. The objective lens having large focal length and large aperture. The eyepiece having small focal length and the small aperture. The objective lens of the astronomical telescope forms the real, diminished and the inverted image of the distant object. The final image formed by the eyepiece between the near and the far points of the normal human eye. The final image formed by astronomical telescope is virtual in nature. Is this topic Permanent Magnet Generator Design hard for you? Watch out for my coming posts.

ii) Terrestrial telescope: The terrestrial telescope is an optical instrument, which is used to see the magnified erect image of distant objects placed on the earth. In case of astronomical telescope, the final image is inverted with respect to the object. To get rid of the inversion of final image we inserted one more convex lens between the objective lens and eyepiece. Therefore, we get the erect image in case of terrestrial type telescope.

2) Reflecting type telescope: In the reflecting type telescopes, we use the concave mirror or sometimes we use the parabolic reflectors. Reflecting type telescopes are best as compared to the refracting type telescopes. The advantages of reflecting type are—  the reflecting type telescope are free from the chromatic aberrations, image formed by the reflecting type telescopes is brighter than the refracting type telescopes, spherical aberration can be reduced by using the parabolic reflectors, high resolution in image can be obtained by using the mirrors of large apertures.