Interesting comments by David and Robert. I ran across an old usenet thread about portrait lenses where Steve Grimes and others recommended using, among other things, close up lenses (diopters).

So I scarfed a used Vivitar set, taped the #4 (250mm focal length) to a shutter, and it actually did very well. Nice smooth look. Have yet to test it on landscapes, but that's a spring project.