Have you gone to the
Logitech Site and made sure you have the latest drivers ?
Have you tried adjusting the focus ring around the lens ?
Hows your lighting? It's best to use the camera in a well-lit area If you can't do anything to improve the lighting situation, some Logitech video cameras have an option for "Low Light Boost." If there is an option for "Low Light Boost," try enabling the "Low Light Boost" in the QuickCam software.
HTH Don