I always do test renders at smaller resolutions and if I like the general composition of it I will blow it up to a decent size. Usually I make things for my own computer as wallpapers and my computer is set to 1400 by 1050. If I want to print it I will make it larger, but I stick to 300 dpi for print resolution. Where do you find Lightjet? Do you own this machine or is it through a separate printing company?