Assertion: focal length eyepiece | /r/HasProperty | perfect
Facets:
value: for observing nebula star clusters
type: PURPOSE
Source sentences:
text: The 40mm focal length eyepiece (low power eyepiece) is perfect for observing nebula star clusters while the 32mm focal length eyepiece (medium power eyepiece) can help you see planets, surfaces of the moon and bright star clusters.