Question
Fri June 08, 2012 By: Milind Shrivastava

mam, What is the monochromatic abberation in reflecting telescope?

Expert Reply
Mon June 11, 2012
Chromatic aberrations are  wave length  dependent, meaning each color of light is affected differently.  Monochromatic aberrations are independent of wavelength, meaning they affect every color equally.  Pure reflecting telescopes can only suffer from monochromatic aberrations.  Telescopes with lenses can potentially be affected by all seven aberrations.
 

Monochromatic Aberrations

There are five monochromatic aberrations:

  • Coma

  • Spherical Aberration

  • Astigmatism

  • Field Curvature

  • Distortion

Spherical aberration is an axial aberration, one that affects the entire field equally, including the center of the field.  The other four aberrations are off-axis aberrations, affecting the star images increasingly toward the edge of the field but not at the center. astigmatism is the problem of focussing horizontal and vertical axis simultaneously.

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