Gene51 wrote:
Either a focal length wider than 18 (obvious), or learn how to do panoramic stitching, which will give you a more natural look without the extension distortion that accompanies most ultra wide lens images.
This was done with a normal focal length lens (45mm on a full frame camera), using three images, each overlapped 50%
Even though I have a 14mm lens and several zooms that cover 24mm, I rarely find myself going to the wide and ultrawide lenses.