OL3 Map with OSM

HTML

<script src="http://ol3js.org/en/master/build/ol.js"></script>
<link rel="stylesheet" href="http://ol3js.org/en/master/build/ol.css">
<div id="map" class="map"></div>

CSS

.map {
    height: 400px;
    width: 100%;
}

JavaScript

// Create the icon feature (geom + properties)
var iconFeature = new ol.Feature({
  geometry: new ol.geom.Point([-274342,4416425]),
  name: 'Tree'
});
// Set up style
var iconStyle = new ol.style.Style({
  image: new ol.style.Icon(({
    anchor: [0.5, 1],
    anchorXUnits: 'fraction',
    anchorYUnits: 'fraction',
    src: 'http://openlayers.org/api/img/marker.png'
  }))
});
iconFeature.setStyle(iconStyle);

// Create map with OSM base layer and the marker layer
var map = new ol.Map({
    layers: [
    new ol.layer.Tile(
    {source: new ol.source.OSM()}
    ),
    new ol.layer.Vector({
      source: new ol.source.Vector({features:[iconFeature]})
    })],
    renderer: "canvas",
    target: 'map',
    view: new ol.View2D({
        center: ol.proj.transform([-0.5, 39.5], 'EPSG:4326', 'EPSG:3857'),
        zoom: 5
    })
});