par·fo·cal /ˌpɑrˈfokəl/
等焦距
par·fo·cal /(ˈ)pɑrˈfokəl/ 形容詞
Par·fo·cal a. Opt. With the lower focal points all in the same plane; -- said of sets of eyepieces so mounted that they may be interchanged without varying the focus of the instrument (as a microscope or telescope) with which they are used. “the convenience of a microscope with parfocal objective lenses”
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