I was about 50 yards from the cottage using the 28-200mm zoom lens, no idea on the focal length, just picked an FL so that the subject was about 6 frames wide.
Usual reason for the mosaic - to push the pixel count right up so that large prints can be made, or so that you can zoom right in on fine detail. Ten megapixels may sound a lot - but 40 megapixels (a 6-frame mosaic with overlap) looks so much better
All the best,
Nexstar 11 GPS, 2 x Sky 90, M25C, MaximDL, Photshop CS3, Noel Carboni's Photoshop actions, 7 foot Pulsar fibreglass dome, Canon 40D, 100mm macro lens, 28-200mm zoom lens, 17-55mm f#2.8 zoom lens, 100-400mm zoom lens, 1.4x converter, 2x converter.