curved lines can be cured when using panorama-factory stitching software(i wished this feature could be used without using the stitching process. maybe someone could ask the owners.
alternative is altostorms rectiliniar panorama (plugin for photoshop or paintshop pro)
up to 160 degr. -i didnt not yet check but maybe this procedure leads in better superwide-angle shots than using orginal superwides. less distortion of people in the corners.