Zoom Lens

Unlike conventional microscope objectives that have a fixed magnification, zoom lenses can accommodate a wide-range of magnifications by adjusting the distance between individual lenses within the zoom lens body.
These lenses allow for much faster observation in that the magnification can be quickly adjusted by simply rotating the zoom ring on the lens.
While most conventional systems require the use of several different objective lenses in order to achieve a wide magnification range, that same range can be fulfilled with just a single zoom lens.
Since multiple objectives and a turret system are not needed, zoom lenses reduce the size and cost of the equipment.