Once again this forum proves to be one of the most informative resources I can think of for photography. Thank you for all the information.
Other than Ole, is there a resource that makes it easy to understand such things? It turns out I WAS in a store yesterday, Samy's in Hollyweird, looking at old lenses in old shutters and not really having much of an idea of what I was looking at. Since I have only modern lenses (the oldest I have is a Schneider with the chrome outer ring and chrome ringed shutter) I couldn't tell which small, old lenses would cover a 5x7 or an 8x10. I kind of assumed that if a lens is 240+ mm, it would probably cover 8x10, but I really have no idea.
Thanks for whatever you can offer.