Vincent Laforet attaches a Canon 600mm F4 EF lens with a 2X converter to a RED Epic using the (yet to be released) Canon lens adapter. The resulting focal length on the cropped sensor of the Red is approx. 3400mm (equiv.), for a roughly one degree angle of view. The video is shot at 4K, 120fps in RAW.
Read more about the video at: vincentlaforet.com.