Hi Calico,
The preset cameras ( perspective, top, left etc. ) are not directly available to be used as a render camera. As PG mentioned, you would need to use the "copy this view to the render camera" button to copy that view to the render camera. If you don't want to override that particular camera you could create a new one using the popup menu of the Assign button of the Camera param of the Render node and then use the "copy view" button.
Regards,
Jo