Zoom lenses
Zoom lenses, also called parfocal lenses, are a special type of
varifocal optics in which the working distance is kept constant when
changing focal length (i.e. the focus is maintained throughout the
process).
Zoom lenses are often described by the ratio of their longest to shortest focal lengths or by the ration between their maximum to minimum magnification. In this category, we can also find macro zoom and telecentric zoom lenses (Opto Engineering® TCZRS and TCZEL series).
