I'm having a problem with using Umbraco.Media from a nested partial (partial within a partial)

similar to this example: http://our.umbraco.org/Documentation/Reference/Mvc/partial-views

my code goes something like

@inherits Umbraco.Web.Mvc.UmbracoTemplatePage

@{
      // Main Content getting a value from a content picker
       var content = Model.Content.GetPropertyValue("mainContent").ToString();
       string[] nodeIds = content.Split(',');

       //looping through my nodes
       foreach (var node in nodeIds)
       {
           var realNode = Umbraco.TypedContent(node);
           
            if(realNode.HasProperty("bodyText")){
               //render bodytext etc
            }else if(realNode.HasProperty("slideShowImages")){
                //render slideshow
                @Html.Partial("slideshow", realNode)
            }
        }  

}

And then in my slideshow.chtml partial:

@model IPublishedContent

@{
    var Slideshow = Model.GetPropertyValue("slideshowImages").ToString();
    string[] nodes = Slideshow.Split(',');
    foreach(var nodeId in nodes){
      var media = Umbraco.Media(nodeId);
      var defaultClass = "class=\"default\"";
      <img src="@media.url" />
}

But this gives me the error:

The type or namespace name 'Media' does not exist in the namespace 'Umbraco' (are you missing an assembly reference?

How do I re-reference the correct Namespace so that Umbraco.Media works within my nested partial?
I've tried @using Umbraco, Umbraco.Web, Umbraco.Web.Media

is it possible to use Umbraco.Media at the nested level or should I give up?

thanks!

- Tim