Карты Bing, как масштабировать карту?

function init(){
// Load the map
var map = new Microsoft.Maps.Map(
    document.getElementById("myMap"),
    {
        credentials: "YOUR-BING-KEY",
        mapTypeId: Microsoft.Maps.MapTypeId.road
    }
);

// Some sample pins
var locs = [];
var loc1 = new Microsoft.Maps.Location(-10, 0);
var pin1 = new Microsoft.Maps.Pushpin(loc1 , {text: '1'});

var loc2 = new Microsoft.Maps.Location(0, 10);
var pin2 = new Microsoft.Maps.Pushpin(loc2, {text: '2'});

var loc3 = new Microsoft.Maps.Location(10, 0);
var pin3 = new Microsoft.Maps.Pushpin(loc3, {text: '3'});

var loc4 = new Microsoft.Maps.Location(20, -20);
var pin4 = new Microsoft.Maps.Pushpin(loc4, {text: '4'});

locs.push(loc1);
locs.push(loc2);
locs.push(loc3);
locs.push(loc4);

map.entities.push(pin1);
map.entities.push(pin2);
map.entities.push(pin3);
map.entities.push(pin4);
var bestview = Microsoft.Maps.LocationRect.fromLocations(locs);
map.setView({bounds:bestview });

}