A barlow lens increases the magnification of the eyepiece usually by a factor of two.
convex lens in microscope and concave lens in telescope
The objective lens. Which is the large lens on the front of the telescope
-- A refracting telescope must have a lens, otherwise it's not a refracting telescope. -- A reflecting telescope can be constructed without any lens, but if you intend to look through it, then you'll use a little lens for the eyepiece.
It contains an objective lens and a lens in the eyepiece of the telescope.
the three functions of a telescope are the objective lens, the focuser, and the ocular lens
depends what kind of telescope
The objective lens focuses the light entering a refracting telescope.
A reflecting telescope is different from a refracting telescope because a reflecting telescope uses a concave lens, a plane mirror, and a convex lens. While a refracting telescope uses two lens.
The "objective" lens (as opposed to the eyepiece).
The magnification is (0.04) x (the focal length of the telescope's objective lens, in millimeters) .
A reflecting telescope has mirrors, and a refracting telescope has a lens.
spectrum telescope refracting telescope