Which two aberrations do objectives of refracting telescope suffer fro

1.	Which two aberrations do objectives of refracting telescope suffer from? How are these overcome in reflecting telescope?
Answer» The two aberrations that objectives of refracting telescope suffer from are (i) Spherical aberrations: Because of the surface geometry of the lens, sharp point image of star is difficult to obtain on a point. In reflecting telescope, we use parabolic mirror to remove this aberration. (ii) Chromatic aberrations: Different colours of light have different refractive index with respect to glass. Hence different colour would focus at different points. hence image of white object would appear as different colour point images. This is known as chromatic aberrations. in reflecting telescope, image is formed with reflected rays hence this aberration is removed.

Which two aberrations do objectives of refracting telescope suffer from? How are these overcome in reflecting telescope?

Answer»

The two aberrations that objectives of refracting telescope suffer from are

(i) Spherical aberrations: Because of the surface geometry of the lens, sharp point image of star is difficult to obtain on a point.

In reflecting telescope, we use parabolic mirror to remove this aberration.

(ii) Chromatic aberrations: Different colours of light have different refractive index with respect to glass. Hence different colour would focus at different points. hence image of white object would appear as different colour point images. This is known as chromatic aberrations.

in reflecting telescope, image is formed with reflected rays hence this aberration is removed.

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