Assertion: focal ratio | /r/HasProperty | focal length
Facets:
value: simply
type: MANNER
Source sentences:
text: Focal ratio 9.25, Focal length 1200mm"
text: The Focal Ratio (f number) is the Focal Length divided by the Objective Diameter.
text: A larger focal ratio (longer focal length at a constant aperture) increases the system magnification and because it is produced by a lower power objective (with less surface curvature) it minimizes optical aberrations, including chromatic aberrations.
text: The focal ratio of a telescope is simply the focal length divided by the aperture (making sure both measurements are in the same units - focal lengths are usually given in millimeters, but apertures are often given in inches).
text: Before leaving the topic of the objective lens, I think I should bring up the subject of focal ratio - the focal length (distance from the objective to the focus point) divided by the aperture (diameter).
text: A scope's focal ratio is the focal length divided by the aperture; for instance a 100-millimeter refractor with a focal length of 600 millimeters has a focal ratio of f/6.
text: The larger the focal ratio, the longer the focal length at a given aperture, so the larger the image.