Zoom Lens Variogon and Betavaron
„Variogon" is the brand name for a vario-lens made by "Jos. Schneider Optische Werke GmbH". But what is a vario-lens?
It is a lens that has no fixed focal length and can be changed by the user with
certain limitations. This is accomplished without having to bring the image of the subject into focus again and again each time the focal length is changed. A lens of this kind is also known as a zoom lens.