Apple Aperture 2 - Manual (Page 511)

Chapter 18 Creating Slideshow Presentations 511
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You can also create your own custom presets. For example, to prepare for a presentation,
you could create two new slideshow presets: one for your presentation and the other for
your question and answer period. The presentation slideshow can show one image at a
time and be manually controlled, so you can move through the images at your own pace.
Your second slideshow preset, to be used during the question and answer period of your
presentation, can display the same images you just showed in a grid across two displays.
The images can advance automatically and be set to music.
To create or modify a slideshow preset, you choose Aperture > Presets > Slideshow (or
choose Edit from the Slideshow Preset pop-up menu in the Run Slideshow dialog), and
the Slideshow Presets dialog appears.
You can then select a slideshow preset, or create a new one, and specify the settings
you want.