Because light can enter a lens from either side, a lens has a focal point on both sides. With mirrors, on the other hand, light only enters from one side, so they only have one focal point. the apex answer:
The centers of curvature of the two sides of the lens The material the lens is made from
The two lenses used are known as a crown & flint. The combination allows bringing more of the complete spectrum of light to the same focus, reducing chromatic aberration (color fringeing). Some modern refractors use ED or fluorite glass & three or more elements to eliminate chromatic aberration. While these designs are more costly, they allow for shorter focal length (f ratio) telescopes that are smaller & easier to transport.
Because a light ray traversing the lens encounters a change of medium twice ...
once from air to glass, and again from glass to air. Refraction occurs each time
there is a change of the transmission medium.
Front lens - objective Back lens - eyepiece
A barlow lens increases the magnification of the eyepiece usually by a factor of two.
A refracting or refractor telescope is a dioptric telescope that uses a lens as its objective to form an image. The refracting telescope design was originally used in spy glasses and astronomical telescopes but is also used in other devices such as binoculars and long or telephoto camera lenses.There are two basic types of telescopes, refractors and reflectors. The part of the telescope that gathers the light, called the objective, determines the type of telescope. A refractor telescope uses a glass lens as its objective. The glass lens is at the front of the telescope and light is bent (refracted) as it passes through the lens. A reflectortelescope uses a mirror as its objective. The mirror is close to the rear of the telescope and light is bounced off (reflected) as it strikes the mirror
In a simple model there are two: the objective lens and the eyepiece lens
The first telescope was invented by Hans Lipperhey , a Dutch lens grinder, in 1609 when he combined two lenses.
1. The Objective Lens. 2. The Eyepiece Lens.
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.
Front lens - objective Back lens - eyepiece
A barlow lens increases the magnification of the eyepiece usually by a factor of two.
A refracting or refractor telescope is a dioptric telescope that uses a lens as its objective to form an image. The refracting telescope design was originally used in spy glasses and astronomical telescopes but is also used in other devices such as binoculars and long or telephoto camera lenses.There are two basic types of telescopes, refractors and reflectors. The part of the telescope that gathers the light, called the objective, determines the type of telescope. A refractor telescope uses a glass lens as its objective. The glass lens is at the front of the telescope and light is bent (refracted) as it passes through the lens. A reflectortelescope uses a mirror as its objective. The mirror is close to the rear of the telescope and light is bounced off (reflected) as it strikes the mirror
In a simple model there are two: the objective lens and the eyepiece lens
The first telescope was invented by Hans Lipperhey , a Dutch lens grinder, in 1609 when he combined two lenses.
Microscope
Reflecting TelescopeA reflecting telescope uses a lens and two mirrors. The lens is positioned at the eyepiece, and thus the focus, which the two mirrors generated by specifically redirected light. There are two types of reflecting telescopes with one lens and two mirrors, the Newtonian Focus and the Cassegrain Focus.
Reflecting TelescopeA reflecting telescope uses a lens and two mirrors. The lens is positioned at the eyepiece, and thus the focus, which the two mirrors generated by specifically redirected light. There are two types of reflecting telescopes with one lens and two mirrors, the Newtonian Focus and the Cassegrain Focus.
i can understand when you don't get the answer you want so here is the answer: our eye works simillar to telescopes because telescope uses convex lens to create a perfect magnified focused image and the eye too uses convex lens to focus the image however our eye rarely uses the lens to magnify image our eye's lens can autofocus near and far objects which is known as eye accomodation with bulging and stretching of eye's organic lens; decreasing and increasing the focal length of the eye lens whereas this flexible lens is not used in telescope instead two lenses are used.
Johannes Kepler made the keplerian telescope, which consists of two covex objective lens.