(1) Add more light and let the apps automatically set your camera's parameters to pre-programmed norms.
(2) If you want to take manual control of a Mac's webcam, your best choice is ecamm's iGlasses add-on software: http://www.ecamm.com/mac/iglasses/
BTW, Apple has changed the built-in camera's name on newer Macs from "iSight" to "FaceTime" and then to "FaceTime HD." Regardless of the name of your built-in camera, iGlasses works the same with any of the built-in Mac or Apple Display cams.
Note that current iGlasses version does not work with PowerPC apps running in Rosetta compatibility mode, but that is obviously not a limitation on your Lion Mac.
Also, using its software tilt/pan/zoom, especially at maximum effect, may result in reduced image quality. iF iGlasses iS something you think would help you, you can take advantage of ecamm's free demo to see whether it meets your needs before you pay the reasonable cost of this software.