View your slideshows in Aperture
You can view your slideshow in one of two ways in Aperture: in full-screen mode or in the Slideshow Editor.
Preview your slideshow
Select a slideshow album in the Library inspector.
In the Slideshow Editor, do one of the following:
To play your slideshow in the Slideshow Editor: Click the Preview Slideshow button, or press the Space bar.
A playhead moves across photos in the Browser as they appear in the slideshow in the Slideshow Editor. To stop playback, press the Space bar.
To play your slideshow in full-screen mode: Click the Play Slideshow button.
To exit the slideshow, press the Esc key at any time.
Tip: If you have a dual-display system, you can choose which display the slideshow appears on when you click the Play Slideshow button. Choose Aperture > Preferences, and click Appearance. Choose which display you want the slideshow to appear on from the “View Slideshows on” pop-up menu.