I am using Autopano to stitch together multiple flatbed scans of large pieces of flat artwork. It seems to work great. But there is an option in prefs about entering camera/lens EXIF data. I am wondering if adding in the lens focal length would help it be even more accurate. I have asked the scanner manufacture what is the scanner lens equivalent to - they were no help. The scanner is a Epson 10000XL.
You should specify a very high focal length (1000 or 2000 mm) and/or activate the 'multiple view' option if you have autopano giga. The scanner model or focal length don't matter. Bernard