I think the use of the term 83X while true, is most misleading. The Coolpix does a remarkable job when it comes to its optical range which is 83X. This is actually called the zoom range. The math is: The power of the camera’s lens is adjustable from 4.3mm wide-angle to 357mm telephoto that’s 357 ÷ 4.3 = 83. In other words the span of the zoom is 83X.To accomplish the lens is constructed using 16 individual glass lenses. Some are glued together, some are air-spaces. There are 12 lens groups each air-spaced apart. When you zoom, the air-space distance changes and this act cause the power of the lens to change. The span of the zoom is from wide-angle at 4.3mm to telephoto at 357mm.

When photographers discuss their lenses, the fact that the zoom range covers 4.3mm thru 357mm is little understood. This is because a far larger film camera is used as a yardstick that defines lens performance. This is the 35mm film camera that has been with us for nearly 100 years. Because of its popularity, we talk about camera lenses in terms that actually apply only to these venerable camera types. However we can make comparisons

It goes like this: The Nikon Coolpix P900 is a super miniature camera thus it makes miniature images that are only about 18% of the size of the esteemed 35mm camera. The 35mm is actually 5.6X larger. So we multiply 4.3 X 5.6 = 24 and 357 X 5.6 = 2000. Now we can say this Coolplix performs as if the zoom range is 24mm – 2000mm. Now 50mm is considered “normal”. A lens shorter is termed “wide-angle”. A lens longer is termed telephoto. Since 50mm is “normal” at full zoom which is the equivalent of 2000mm, objects will appear 2000 ÷ 50 = 40X larger. In other words a bird in the tree 1000 feet away will image as if it were only 25 feet away.