I'm been kicked out of forums for trying to explain this to nonbelievers. Some people just don't get it. :loco:
But everything out of focus will look very different, and the background will be magnified, making it LOOK more out of focus.
Gregory, no doubt you are referring to your tour of duty in the Great DOF War over on photo.net MF forum a few weeks back:
http://photo.net/medium-format-photography-forum/00Y2tN?
Thankfully, people like you and I prevailed. :thumbup:
To the OP: you'll never see a better explanation of all the nuances surrounding DOF than this:
http://toothwalker.org/optics/dof.html
You do have the right idea that a longer distance from the subject will increase DOF. But if you counterbalance that by using a longer focal length lens (at the same f-stop) to make the image the same size within the frame, then that increase is exactly neutered, and you're back to where you started. Gregory is right about the background
looking more oof with the longer lens, but your concern is not the background, it's the 2nd eye of the subject. The only solutions therefore are:
1) stop down the lens more, or
2) move further back and crop in, or
3) stay where you are, use a shorter focal length lens, and crop in.
Ray