Assertion: newtonian telescope's mirror | /r/HasProperty | offset towards primary mirror
Facets:
value: correctly
type: MANNER
Source sentences:
text: To center the fully illuminated field of view, the secondary mirror should be offset towards the primary mirror, as seen from the center of outer rays (this is the point where the primary mirror appears to exactly fill the face of the secondary).
text: If the secondary mirror is correctly offset towards the primary mirror, it will appear centered when seen from a point near focus - but if you move your eye far away from focus, you will no longer see it centered.