I'm thinking of printing some images out. How do I work out at what resolution I need to render at for a certain size paper. For instance if I want to print out to A3 what's the minimal resolution I would need to render at without the quality suffering? Is there some kind of calculation I can use to work this out depending on the size of the print? If I render really high res it won't do any harm but will take ages to render, render to low and image will suffer.