The G12 has a 5 to 1 zoom lens with focal lengths ranging from 6.1 mm on the “wide angle” end to 30.5 mm on the “telephoto” end. The lens is not infinitely adjustable; there are 14 different focal lengths. The available focal lengths are:
6.1 mm 12.1 mm 6.8 13.8 7.4 15.7 8.1 18.1 8.9 21.5 9.8 25 10.8 30.5
These are the focal lengths needed to do depth of field calculations using programs like DOFMaster. There is also a DOFMaster App for the iPhone that is very handy and accessible in the field. The iPhone App does not always have the precise G12 focal length as part of its database. For those focal lengths, I just use the closest available value.