var map;

function initialize() {
    var mapCanvas = "map_canvas";
    var mapLat = 45.12381;
    var mapLng = -123.11379;

    var point = new google.maps.LatLng(mapLat, mapLng);

    var mapOptions = {
        zoom: 4,
        center: point,
        mapTypeId: google.maps.MapTypeId.SATELLITE
    };

    map = new google.maps.Map(document.getElementById(mapCanvas), mapOptions);

    // WORK
    map.setZoom(15);
}

google.maps.event.addDomListener(window, 'load', initialize);

// DON'T WORK ???
map.setZoom(19);