Although you're well into the difraction area, shooting at a shutter speed of 1/30, on a monopod, you might get a little camera movement. For landscape, maybe the best is to use a sturdy tripod with a cable release (or self-timer optino on your D80). Try not to go beyond f/16, f/11 is best, and focus at the hyperfocal distance (you can get really nice hyperfocal charts here in nikonians forums).
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