You can check the focus, color, and lighting of your high-resolution digital stills using the Cinematography window. This is available under the Window menu and can also be accessed using Command-E/Ctrl-E.
You can play back proxies of your high-resolution stills in the animation window. To do this, press the button that has four small diamonds in the shape of a larger diamond. This toggles between video assist images and proxies of high-resolution images.