From Canon:
Firmware Version 1.0.2.0 incorporates the following fix:
Fixes a phenomenon in which the focal length may not change when the control ring's function is to control the step zoom, and the control ring is turned slowly, click-by-click. (In AUTO, SCN, or Movie mode, the default function for the control ring is to control the step zoom.)
* Please note that this phenomenon does not always occur with every affected product.
Firmware Version 1.0.2.0 is for cameras with firmware Version 1.0.1.0 or Version 1.0.0.0. If the camera's firmware is already Version 1.0.2.0, it is not necessary to update the firmware.
Please note that, once the camera is updated to the latest version, it cannot be restored to a previous version.
How to Identify Cameras eligible for the Firmware Update:
All PowerShot S100 Digital Compact Cameras are eligible for this firmware update.
Download:
Canon PowerShot S100 Firmware v1.0.2.0: Windows | Macintosh
Adorama carries the Canon PowerShot S100 Digital Camera.