A telescope is an optical instrument that magnifies and enhances the view of distant objects. The objects could be either astronomical or terrestrial.
There are two types of telescopes: reflecting and refracting telescopes. The reflecting and refracting telescopes differ in their way of manipulating the incoming light rays to magnify the image.
- Reflecting telescopes use mirrors to reflect light while refracting telescopes use lenses to refract light.
- Reflecting telescopes tend to be more compact and portable than refracting telescopes.
- Refracting telescopes are better suited for observing planets and stars with clear, crisp images.
Reflecting vs. Refracting Telescopes
Reflecting telescopes use mirrors to reflect and focus light while refracting telescopes use lenses to bend and focus light. In a refracting telescope, the light enters through a large lens at the front of the telescope. The light is then bent and focused to a point at the other end of the telescope, where the eyepiece is located.
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In a reflecting telescope, the main component is a mirror which bounces the light rays and then focuses them into a small area. On the other hand, a refracting telescope uses lenses to focus the light rays as it travels toward the other end of the telescope.
|Parameters of Comparison||Reflecting Telescopes||Refracting Telescopes|
|Definition||A telescope has a single or a combination of curved mirrors that reflect the light rays and form an image.||An optical telescope has a lens as its objective lens to form an image.|
|Tube||An open tube makes it vulnerable to dust, humidity, etc.||It has a closed tube that protects it against humidity and dust.|
|Light Gathering Power||It has a large mirror that has more light-collecting capacity.||It has a small diameter that has a light collecting capacity.|
|Chromatic Aberrations||It suffers no chromatic aberrations (colored fringes around stars).||It suffers chromatic aberrations (colored fringes around stars).|
|Weight||It is heavy and bulky.||It is light and transportable.|
|Use||Have more use in the field of astronomy.||Have more use in the field of photography.|
What are Reflecting Telescopes
A reflecting telescope is an optical telescope with a single or a combination of curved mirrors used to reflect the light rays and form an image.
It consists of a primary mirror located at the lower end of the telescope tube, and the front surface is coated with a very fine thin film of metal such as aluminum. The back side of the mirror is mostly made up of glass.
The primary mirror of a reflecting telescope reflects the light to the focus. The primary mirror has either a concave spherical or a parabolic shape, and when it reflects the light rays, the image gets inverted at the focal plane.
The reflecting telescope does not suffer chromatic aberrations as reflected light does not get dispersed according to its wavelength. The telescope tube is shorter, hence reducing the tube’s cost.
The reflecting telescopes are heavy, produce disappointing optical quality, and have an open tube, making them vulnerable to dust and humidity compared to the refracting telescopes.
Reflecting telescopes have their use in the field of astronomy research.
What are Refracting Telescopes
A refracting telescope is an optical telescope that uses a lens as its objective lens to form an image of a distant object.
The refracting telescope consists of two lenses, one is the Objective, and the other is the eyepiece. The objective lens produces an image of a distant object at its focal point, and the eyepiece lens magnifies the image formed.
A refracting telescope has good contrast and sharpness, is light and transportable, and has a closed tube that protects it against humidity and dust.
A refracting telescope suffers chromatic aberrations (colored fringes around stars), cannot be made of larger size, and has a small diameter with less light collecting capacity than reflecting telescopes.
Refracting telescopes are used in astronomy, photography, and spy glasses. They are used in binoculars and camera lens systems because of their simple design and lower construction cost.
Main Differences Between Reflecting and Refracting Telescopes
- A Reflecting telescope has a single or a combination of curved mirrors that reflect the light rays and form an image. On the other hand, a refracting telescope has a lens as its objective lens to form an image.
- Reflecting telescopes use mirrors, whereas refracting telescopes use lenses.
- Reflecting telescopes have fewer chromatic aberrations, whereas refracting telescopes have chromatic aberrations.
- Reflecting telescopes have disappointing optical quality, whereas refracting telescopes have excellent contrast and sharpness.
- Reflecting telescopes have a large mirror with more light-collecting capacity, whereas refracting telescopes have a small diameter with less light-collecting capacity.
- Reflecting telescopes are heavy and bulky, whereas refracting telescopes are light and transportable.
- Reflecting telescopes can be made larger, which is impossible with refracting telescopes.
- Reflecting telescopes have an open tube making them highly vulnerable to dust and humidity, whereas refracting telescopes have a closed tube that protects them against humidity and dust.
- Reflecting telescopes have a lower construction cost, whereas refracting telescopes have a higher construction cost.
- Reflecting telescopes produce issues in their maintenance and cleaning, whereas refracting telescopes have nonexistent maintenance and cleaning issues.
- Reflecting telescopes are used in the field of astronomy, whereas refracting telescopes are used in the field of photography.
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Piyush Yadav has spent the past 25 years working as a physicist in the local community. He is a physicist passionate about making science more accessible to our readers. He holds a BSc in Natural Sciences and Post Graduate Diploma in Environmental Science. You can read more about him on his bio page.