Optical Instruments – Astronomical Telescope

Astronomical Telescope

Objective lens: Lower power
Eye lens: Higher power

Position of the object: At infinity
Nature of the image, I₁: Real, inverted and magnified

Position of the image, I₁: At the principal focus of object lens, f_o.
Nature of the image, I₂: Virtual, inverted and smaller in size.

Distance in between the two lens

1. The distance between the object lens and the eye lens in an astronomical telescope is equal to the sum of the focal length (f_o + f_e).
2. If the distance between both lenses is bigger than (f_o + f_e), no image can be seen.

Magnification of the astronpmical telescope.