public void SetCamera( 
   Layer layer,
   bool useSelectedFeatures
)

//Creates a new map frame and changes the camera's scale.

//Constuct on the worker thread
await QueuedTask.Run(() =>
{
  //Build geometry
  Coordinate2D ll = new Coordinate2D(6.0, 8.5);
  Coordinate2D ur = new Coordinate2D(8.0, 10.5);
  //At 2.x - Envelope env = EnvelopeBuilder.CreateEnvelope(ll, ur);
  Envelope env = EnvelopeBuilderEx.CreateEnvelope(ll, ur);

  //Reference map, create MF and add to layout
  MapProjectItem mapPrjItem = Project.Current.GetItems<MapProjectItem>().FirstOrDefault(item => item.Name.Equals("Map"));
  Map mfMap = mapPrjItem.GetMap();
  //At 2.x - mfElm = LayoutElementFactory.Instance.CreateMapFrame(layout, env, mfMap);
  //         mfElm.SetName("New Map Frame"); 
  mfElm = ElementFactory.Instance.CreateMapFrameElement(layout, env, mfMap, "New Map Frame");

  //Set the camera
  Camera camera = mfElm.Camera;
  camera.Scale = 24000;
  mfElm.SetCamera(camera);
});

//Zoom map frame to the extent of a single layer.

//Perform on the worker thread
await QueuedTask.Run(() =>
{
  //Reference MapFrame
  MapFrame mf = layout.FindElement("Map Frame") as MapFrame;

  //Reference map and layer
  Map m = mf.Map;
  FeatureLayer lyr = m.FindLayers("GreatLakes").First() as FeatureLayer;

  //Set the map frame extent to all features in the layer
  mf.SetCamera(lyr, false);
});

//Change map frame extent to single feature with 10 percent buffer

//Process on the worker thread
await QueuedTask.Run(() =>
{
  //Reference the mapframe and its associated map
  MapFrame mf = layout.FindElement("Map Frame") as MapFrame;
  Map m = mf.Map;

  //Reference a feature layer and build a query (to return a single feature)
  FeatureLayer fl = m.FindLayers("GreatLakes").First() as FeatureLayer;
  QueryFilter qf = new QueryFilter();
  string whereClause = "NAME = 'Lake Erie'";
  qf.WhereClause = whereClause;

  //Zoom to the feature
  using (ArcGIS.Core.Data.RowCursor rowCursor = fl.Search(qf))
  {
    while (rowCursor.MoveNext())
    {
      //Get the shape from the row and set extent
      using (var feature = rowCursor.Current as ArcGIS.Core.Data.Feature)
      {
        Polygon polygon = feature.GetShape() as Polygon;
        Envelope env = polygon.Extent as Envelope;
        mf.SetCamera(env);

        //Zoom out 15 percent
        Camera cam = mf.Camera;
        cam.Scale = cam.Scale * 1.15;
        mf.SetCamera(cam);
      }
    }
  }
});