Did you see Litst's post describing the "Procedural Skydome"? - new scene - insert an infinite plane - insert a sphere - open the Properties tray - disable the Casts Shadows checkbox - click on the clap icon to get to the Motion/Transform tab - set the dimensions of the sphere to something around 1000 x 1000 x 500 inches - set the X,Y and Z centers of the sphere to 0 He also used the 2X1 aspect ratio for the texture. My guess is that the background image has to be double the render size in pixels.