The resolving power of a refracting telescope increases with the diameter of the spherical objective lens. In reality, i
Posted: Fri May 06, 2022 6:43 am
The resolving power of a refracting telescope increases with the diameter of the spherical objective lens. In reality, it is impractical to increase the diameter of the objective lens beyond approximately 1 m. Why?
If the objective lens is too large, it is difficult to keep it clean.
The resulting increase in light scattering from the surface of the objective lens will blur the image.
The increasing size of the objective lens will cause chromatic aberration to grow worse than spherical aberration.
The resultant sagging of the mirror will cause spherical aberration.
The spherical objective lens should be replaced by a paraboloidal objective lens beyond a 1-m diameter.
If the objective lens is too large, it is difficult to keep it clean.
The resulting increase in light scattering from the surface of the objective lens will blur the image.
The increasing size of the objective lens will cause chromatic aberration to grow worse than spherical aberration.
The resultant sagging of the mirror will cause spherical aberration.
The spherical objective lens should be replaced by a paraboloidal objective lens beyond a 1-m diameter.