Simplest Telescope | Hindi

This really Simple Telescope was designed by SASTA – the South African Agency for Science & Technology. The telescope’s tube consists of 3 cardboard tubes, each 30-cm long. There are two lenses – the BIG OBJECTIVE is Convex-concave and the SMALL EYEPIECE is Concave-concave.
The three tubes of slightly different diameters fit into each other and can easily slide. Thus the length of the tube can be increased and decreased. The sliding of the tubes helps in adjusting the focal length to view far and near objects clearly. These sliding tubes are called as TELESCOPIC TUBES. This is the small eyepiece with a focal length 4-cm and diameter of 1.8-cm. The larger OBJECTIVE LENS has a focal length of 70-cm and a diameter of 6.7 cm. Hold both lenses in your hands and adjust the distance between them to see a far away object clearly. This schematic diagram shows the RAY DIAGRAM of the telescope. First glue the outer rim of the EYEPIECE on the lens holder. Then glue the EYEPIECE to the small end of the tubes. The tubes can easily expand / contract and help you in getting a clear image of a far away object. Finally glue the BIG OBJECTIVE on the big end of the tubes. Now the telescope is ready. In the expanded position the telescope might be 85-cm long. In the contracted position it might be just 30-cm long. Now point the big lens towards what you wish to observe. Adjust the focal length by sliding the tubes. Soon you will see a clear image of your desired object. You can watch birds, wild life or gaze at the moon with this SIMPLEST TELESCOPE.

This work is supported by IUCAA ( and TATA Trust (

Credits:,Ashok Rupner, Manish Jain, Pradnya Pujari, Shivaji Mane, Jyoti Hiremath, Arvind Gupta, Vidula Mhaiskar TATA Trust: Education is one of the key focus areas for Tata Trusts, aiming towards enabling access of quality education to the underprivileged population in India. To facilitate quality in teaching and learning of Science education through workshops, capacity building and resource creation, Tata Trusts have been supporting Muktangan Vigyan Shodhika (MVS), IUCAA’s Children’s Science Centre, since inception. To know more about other initiatives of Tata Trusts, please visit

Post time: Sep-10-2017