You can create stacks in two ways: specify that Aperture create stacks automatically, or you can create stacks manually. For example, if you shoot a series of photos in quick succession (such as at a sports event) or if you bracket photos to allow for differences in lighting or exposure, you most likely will want to view those photos together. Aperture can stack those photos automatically based on metadata recorded by the camera as the series of pictures is taken.
You can also have Aperture automatically group new versions of the same photo as you create them.
Stack photos automatically
In the Library inspector, select a project or an album that contains the photos you want to stack.
Choose Stacks > Auto-Stack (or press Option-Command-A).
In the Auto-Stack Images HUD, drag the slider to specify the maximum interval for successive shots in a stack.
As you drag the slider, the photos in the Browser are stacked according to the interval of time specified. For example, if you typically shoot a series of related photos in 15-second intervals, set the slider to 15 seconds.
Inspect the stacks to determine if the time interval should be shortened or lengthened.
Note: You can also manually select photos in the Import browser and stack and unstack them using the same commands and procedures you use to stack photos in the Browser.
Create new version stacks automatically
Choose Aperture > Preferences, or press Command-Comma (,).
The Aperture Preferences window appears.
Click the General button, then select the “Automatically stack new versions” checkbox.
Create a stack manually
After importing photos, you may want to quickly review them and delete those that you immediately see have technical or content flaws. You may then want to group the remaining photos into stacks before rating them. Stacking photos manually can help provide an initial organization and an overview of your shots, which you can then put through a more refined or discriminating rating pass later.
In the Browser, select the photos you want to stack.
You can Shift-click adjacent photos and Command-click nonadjacent photos to select them.
Tip: To quickly select a series of photos, select a photo at one end of the series, hold down the Shift key and press the Right Arrow or Left Arrow key to select additional photos.
Choose Stacks > Stack (or press Command-K).
The selected photos are now stacked and appear linked in gray. The Stack button appears as an overlay on the top-left portion of the current pick photo in the Browser. You can change the pick photo and rearrange the order of the photos in the stack as you wish.
Unstack a selection of photos
After creating a stack, choose Edit > Undo, or select a photo in the stack and choose Stacks > Unstack (or press Shift-Command-K).