Camera Raw 4.1 and later add a very useful feature that appeared first in Lightroom. If you want to inspect an image closely for dust or other defects that need retouching, the Page Down key takes you through the entire image, from the top left corner to the bottom right corner. Here’s how it works:
1. In Camera Raw, zoom to 100% view or higher.
2. Press the Home key to view the top left corner of the image.
3. Press the Page Down key to move down one screen.
4. Press Page Down again to move down another screen. This is the cool part: If you hit the bottom of the image and press Page Down, Camera Raw automatically jumps to the top of the image one screen to the right! This means that all you have to do to check the entire image is keep pressing Page Down, until you reach the bottom right corner of the image.
On notebook computers without separate Home, End, Page Up, or Page Down keys, remember that they may be available as second functions on your arrow or other keys. For example, on Mac notebooks, these four functions are overlaid on the four arrow keys, and invoked when you also press the Fn (function) key. So to use Page Down, you’d press Fn+Down Arrow.