What is the adjustment, or parfocalizing, distance of a microscope?
These terms refer to the chosen distance from the opening of the nosepiece to the focused specimen (in most modern microscopes the distance measures 45mm). A standard distance for all objectives makes it easy to rotate a sequence of objectives into the light path with a minimum of refocusing. Such a battery of objectives is described as parfocal. If a focused feature remains centered in the field of view as you change objectives, the objectives are also described as parcentric.
