Optional lens converters
If the 12x zoom lens on the S2 IS isn't enough for you Canon has two lens adaptors available to give you even wider - and even longer - focal lengths. The TC-DC58B (1.5x teleconverter) and WC-DC58A ( 0.75x wide converter) have to be screwed into the LAH-DC20 Lens adaptor/hood set (which attaches to the bayonet on the front of the S2) and extend the focal length range to 648mm and 27mm, respectively. A menu option allows you to tell the S2 you've attached an adaptor, meaning the IS system can be optimised for a specific converter.
We tried the converters out and found them to be better than expected, producing very little loss of sharpness (though both exaggerate the fringing problem slightly). Here's a couple of examples to show the difference they make.