3 : Parts Of Telescope

Question 1

• a compound lens composed of crown and flint glass mounted in the objective end of the telescope and has its optical axis concentric with the tube axis
• allows light rays to enter the telescope and form an image of the object sighted within its field of view

Answer 1

Objective Lens

Question 2

• a form of microscope containing either 2 or 4 lenses used to enlarge altogether the image and the cross hairs
• allows the instrument man to sight and read accurately the graduations on a leveling rod

Answer 2

Eyepiece

Question 2

• consists of a pair of lines which are perpendicular to each other and are used to define the instrument’s line of sight
• internal focusing telescope – have an additional auxiliary lens which moves back and forth between the objective and the cross hairs as the focusing screw is turned

Answer 2

Crosshairs

Question 3

ratio of the apparent size of an object viewed through a
telescope to its size as seen by the unaided eye from the
same distance (expressed in diameters)

Answer 3

Magnification

Question 4

a sealed graduated glass tube containing some amount of liquid an a small air bubble

Answer 4

Level Vial

Question 5

• a type of bubble used on most modern and precise instruments such as the tilting and automatic levels
• employs an optical device which splits the bubble longitudinally then turns one end around to make it appear adjacent to the other end

Answer 5

Coincidence Bubble

Question 6

• serves as a base to prevent movement of the instrument after it is set up
• consists of three wooden or aluminum legs which are securely fastened to the tripod head by means of a hinged point
• fixed-leg tripod – a tripod whose legs are made of solid wood
• extension tripod – a tripod whose legs have a sliding section

Answer 6

Tripod

Question 7

• a pointed piece of metal attached at the end of a tripod
• the tripod is forced into the ground by stepping on it with one’s foot

Answer 7

Shoe