Q: How can I fix internal mic static when recording using photo booth, etc.?

http://support.apple.com/kb/HT2090 How to Troubleshoot iSight

If you mean the internal mic(s) in your old external, Firewire-connected, iSight, try the suggestions from Boomer's link.

If you mean your Mac's internal mic, understand that Mac's internal mic has nothing to do with any camera built into any Mac.  Consider the suggestions in iMovie '11: Reduce background noise ...  If that doesn't help you, you likely have a hardware problem.  Contact Apple or an Apple-Authorized Service Provider for service.

If you need more help, when you post back, be sure to tell us:

Which Mac (model and production date) is giving the problem,

Whether you are using an external iSight,

What Mac OS X version you use, and

Which iMovie and Photo Booth versions are exhibiting the static.