Assertion: newtonian telescope's mirror | /r/AtLocation | spherical
Facets:
value: in large focal ratios optical assemblies
type: OTHER
Source sentences:
text: In large focal ratios optical assemblies, both primary and secondary mirror can be left spherical and a spectacle correcting lens is added between the secondary mirror and the focal plane (catadioptric Yolo).
text: Smaller, longer focus mirrors can be left spherical - which is the easiest to make and test mirror shape - but will have residual amounts of spherical aberration (FIG.
text: A concave mirror focuses light, but if the mirror is left spherical the light is not all focused to the same point.
text: However, if the aperture is small enough and the focal ratio large enough, the mirror can be left spherical as the difference between a sphere and parabola is negligible.