of or pertaining to different eyepieces (of telescopes or microscopes) that all focus their images in the same plane, so that they can be interchanged without readjusting the instrument.
Main Entry: par·fo·cal Pronunciation: (')pär-'fO-k&l Function: adjective : 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/-fO-'kal-&t-E/nounplural-ties
[pahr-foh-kuh
l] 