The zoom level of the camera.
A zoom of 0.0, the default, means the screen width of the world is 256. Adding 1.0 to the zoom level doubles the screen width of the map. So at zoom level 3.0, the screen width of the world is 2³x256=2048.
Larger zoom levels thus means the camera is placed closer to the surface of the Earth, revealing more detail in a narrower geographical region.
The supported zoom level range depends on the map data and device. Values beyond the supported range are allowed, but on applying them to a map they will be silently clamped to the supported range.
final double zoom