The advantage of a Zoom Optical System over a conventional system is that a large range of
magnifications form 30X - 80X standard and 60X - 160X with optional 20X Eyepiece can be used interchangeably on examination of the Object. A low magnification can be used to see a large area and without re-adjusting the Focal Length, a turn of the zoom knob gives high magnification for more detail studies of a section. The cross hair location will not be changed through this zooming feature.
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