Assertion: mm eyepiece | /r/HasProperty | to give wide field of view
Facets:
Source sentences:
text: A 40 mm eyepiece will give a nice low magnification in an f/10 refractor or in a Schmidt-Cassegrain, but it must be have a two-inch barrel and be used in a two-inch focuser, if it is to give a wide field of view, as well.