When I have several images that are all tiled and I need to zoom in or out on one of them without changing the size of the window, I toggle off Preference / General / Zoom Resizes Window. If you prefer to leave your preference toggled on, then you can temporarily stop the window from resizing by adding the Option (Mac) / Alt (Win) key to the old standby - Command (Mac) / Control (Win) “+” (plus) to zoom in, Command (Mac) / Control (Win) “-” (minus) to zoom out. If I remember correctly, I believe that this default behaviors are reversed on the Windows platform (ie zooming doesn’t resize the window by default) but you can still customize your preference on either platform.
With the Zoom tool selected, checking Zoom All Windows (in the Options bar) will zoom all open documents at one time. If you don’t want the option on constantly, simple use the Shift key to temporarily toggle on/off the Zoom all Windows feature while zooming.
A new, quick way to move to another part of the image is with the new Birds-Eye View - select any tool, hold down the “H” key (to temporarily select the Hand tool) to “crash”-zoom in on an area. Reposition the rectangle to zoom in to another area, and release the Hand tool to zoom in on that area. In PSCS4, if you zoom in above 600%, a new Pixel Grid is displayed on top of the image (toggle Pixel View under View > Show Pixel Grid).
Photoshop CS4 can display images much faster depending on the system’s hardware-accelerated display and Open GL capabilities. In addition, the on-screen jaggies that you use to see at uneven zoom levels like 33.3% are now rendered smooth. Hoking into the Open GL capabilities also allows PSCS4 users to select the Zoom tool and click and hold in the image the to zoom in continuously. Add the Option to zoom out. Sweet!
PS CS4 supports ”Flick Panning”. While using the Hand tool to move left, right, up or down in an image (click, drag and hold for legacy behavior). Flick Panning does require Open GL and can be toggled off in the Preferences / General. While in the Preferences be sure to try Zoomed Click Point to Center which centers the location of the cursor click point to the center of the screen. And don’t forget, Option (Mac) / Alt (Win) + spacebar will temporarily give you the Zoom Out tool while another tool is selected while Command (Mac) / Control (Win) + spacebar will temporarily give you the Zoom In tool while another tool is selected.
In Photoshop CS4 we’ve added the shortcut Cmd (Mac) / Ctrl (Win) + 1 to set the zoom level to 100% (also known as Actual Pixels). This brings PSCS4 into alignment with other Creative Suite Applications such as Illustrator, InDesign, and Flash. If the shortcut doesn’t feel right, you can customize it to your liking using the Keyboard shortcut editor (Edit/Keyboard Shortcuts). Or, you can double click on the Zoom tool to display the image at 100%. In addition, the old standby’s will still work - Command (Mac) / Control (Win) “+” (plus) will zoom in, Command (Mac) / Control (Win) “-” (minus) will zoom out.
The forward slash key (/) toggles on and off the Shield (the shading of the area outside of the crop) while using the Crop tool.