In Silverlight Bing Maps we can define level of zoom to our location center between 1 to 19 values. "Zoom Level 19" is closest level and "Zoom Level 1" is the farthest level to the earth.
we can define zoom level in
XAML code with ZoomLevel Property
<
Microsoft_Maps_MapControl:Map x:Name="MapIK" ZoomLevel="10"/>
or define dynamicly in
C#
MapIK.ZoomLevel = 19;
Zoom Level = 4
Zoom Level = 10
Zoom Level = 16
Zoom Level = 19
All the best.