No this method allows for only one render. Because you disable the cast shadows for the large sphere group, the sun will act normally. When you apply the HDRI image ti it, click the button for ambience as bot ambient channels in the mat lab, and nothing else. No diffusion or anything. This will ensure that the image is always exactly as bright as is supposed to be, and it won't be effected by other scene lights. To get the FOV aligned, it's just trial and error adjustments until I can post the actual specs. What do you mean by "only up to a distance?" You just have to align the camera's sight path with the edge of the hole. If you do this right, it works fine for spheres, because the spheres are behind the edge enough that they have the correct reflections. As I said I am sorry I can;t show a more complete tutorial yet. I assure you when it's done it will be easier to see. Check my next post for an example image.