@LarryStudios, you being a PC guy explains why you don't need the Webcams Settings app. While Logitech webcams work greatly on Windows, since they are fully *biased* optimised for the OS, on a Mac, they have extremely limited functionality (no manual focus, no manual white balance). The Webcam Settings app is a workaround which allows us Mac users to have access to the full features, needed for brickfilming, of webcams.
@Antonio Ferrara, sorry for taking a while to get back to you, but I can now confirm that all manual features are accessible on the Logitech c920 through the Webcam Settings. It also works with the c910, too. I'd recommend investing in a c910 or c920 paired with Webcam Settings, not a Pro 9000 (sorry Larry!), purely because they are newer, have far greater specs, and also go for around $100. You may have to order them online if they're not available in your area...