Greetings: I am reading the great tutorial at http://backingwinds.blogspot.com/2006/10/how-to-create-professional-hdr-images.html and he says to adjust the shutter speed and not the aperture. Well, he then goes on to say he takes a photo at metered EV, then -2EV, -4EV, -6EV, +2EV, +4EV, +6EV. Forgive me for being so new to this but what in the world is EV? I'm shooting on a Nikon D80 and want to figure out what to set it to. Thanks!