Reflecting vs Refracting Telescopes

• What are the two main types of telescopes?

  Refracting and reflecting telescopes
• What are the two main types of aberration affecting telescopes?

  • Chromatic aberration
  • Spherical aberration

  
• What is chromatic aberration?

  Image distortion in refracting telescopes

  
• Why does chromatic aberration occur in refracting telescopes?

  Different wavelengths of light are refracted differently
• How does the wavelength of blue light compare to red light in terms of refraction?

  Blue light is refracted more than red light
• What happens to different colors of light in a refracting telescope?

  They focus at different points
• What is the result of chromatic aberration in images?

  Multi-colored blurred edges
• Can chromatic aberration be completely eliminated?

  No, but it can be significantly reduced
• How can chromatic aberration be reduced in telescopes?

  By using a second diverging lens

  
• Why does chromatic aberration not occur in reflecting telescopes?

  Mirrors reflect light, they do not refract
• What is spherical aberration?

  Image distortion due to spherical curvature

  
• How does spherical aberration affect light rays?

  They focus at different points
• What happens to the focal length of light rays further from the principal axis?

  Their focal length becomes shorter
• How can spherical aberration be reduced in refracting telescopes?

  By using a parabolic lens

  
• What is the limitation of using a parabolic lens in refracting telescopes?

  Increases size and weight of the lens
• How can spherical aberration be completely overcome in reflecting telescopes?

  By using a parabolic mirror

  
• What are the advantages of refracting telescopes?

  • Require less maintenance
  • Not sensitive to temperature changes
• What are the disadvantages of refracting telescopes?

  1. Difficult to make large lenses
  2. Heavy and difficult to maneuver
  3. Weakness in lens construction
  4. Suffer from chromatic and spherical aberration
  5. Limited to visible light observation
• What are the advantages of reflecting telescopes?

  1. Larger diameter mirrors for greater magnification
  2. Lighter and easier to support
  3. Fewer construction issues
  4. No chromatic aberration
  5. Can observe non-visible wavelengths
• What are the disadvantages of reflecting telescopes?

  • Secondary mirror blocks some light
  • Requires regular maintenance
  • Possible chromatic aberration in eyepiece
• What effect does the secondary mirror have on the image clarity in reflecting telescopes?

  It slightly reduces light reaching the aperture
• What should be focused on when comparing refracting and reflecting telescopes?

  Optical differences only