Assertion: telescope's ratio | /r/HasProperty | important
Facets:
value: very
type: DEGREE
value: for visual observing
type: PURPOSE
value: photographically
type: DEGREE
Source sentences:
text: Focal ratio is very important photographically because it determines how quickly a picture can be taken.
text: For visual observing, focal ratio is pretty unimportant.
text: Focal length and focal ratio are more important factors that affect what a telescope is good for and therefore can help you to determine if a certain telescope is right for you or not.