parfocal

par·fo·cal

adj \(ˈ)pär-ˈfō-kəl\

Definition of PARFOCAL

: having corresponding focal points all in the same plane : having sets of objectives or eyepieces so mounted that they may be interchanged without varying the focus of the instrument (as a microscope) with which they are used

—par·fo·cal·i·ty \-fō-ˈkal-ət-ē\ noun, plural par·fo·cal·i·ties