This is a site offering a Lighting ratio cheet sheet PDF. The Canon 580 and Nikon's 800 settings are mentioned. I think it could be a very useful PDF for you to print out and place in a folder for future use. Very useful for portrait, in studio work, landscape and wedding photography photographers to quickly get a light setting right. Of course once you learn the ratios etc you won't need it but while just starting out you should at least take a look at it.