I have the Nikon D70s -- good camera so far; I've decided to buy an external flash and am stuck between the sb-600 or 800 models. Whats the deal with this 'automatic remote flash' business that I keep reading about? I can set the flash to the side a few feet away and expect it to trigger when I take a pic? Why would I want that anyway? Does the sb-600 offer this as well? The 600 is $187 and the 800 is $306 -- big price diff! For a totally amateur 'photographer', which is the way to go?