When viewing multiple images simultaneously, Shift -drag with the Hand tool to pan all open documents. Similarly, shift -clicking with the Zoom tool will zoom all images simultaneously. To set this as the default behavior, with the Zoom or Hand tool selected, check the “Zoom all Windows” and/or “Pan all Windows” in the Option bar.
If you find that you have a dialog box up or you’re in a modal state like Free Transform, you can always use the shortcuts Command (Mac) / Control (Win) + Plus (+) or Minus (-) to zoom in and out. And if you need to pan, use the Spacebar to temporarily give you the Hand tool.
With the Hand tool selected, checking Scroll All Windows (in the Option bar) will scroll (or pan) all open documents at once. Shift -drag (or pan) with the Hand tool to temporarily turn on the Scroll All Windows.
Double clicking the Hand tool in the Tool Panel is the same as selecting View > Fit on Screen (Photoshop will display the entire image as large as possible on screen. Note: Command (Mac) / Control (Win) + 0 (zero) also displays the image as large as possible.
Holding down the spacebar (while most other tools are selected) will temporarily give you the Hand tool allowing quick panning of images that are zoomed in.
