What is a Zoom Level?
The zoom ratio is used to indicate the power of the lens, rather than the focal length.
You will see it listed in the advertising with an X, such as 3X or 10X.
The zoom ratio is the value of the longest focal length of the lens divided by its shortest focal length. So, the zoom ratio for a 20-500mm lens is 500mm÷20mm, or 25X.