I have been looking at various Aperture video-tutorials at apple.com. And one thing they talk about is the flexible library-management and previews that can save space on the HD. Now, how that relates to me: I have a MBP, and I have a bunch of external hard-drives. Since I want to save HD-space, I would like to put my Aperture-library on the external HD. And that works just fine. But I would like to have those images available even when I'm out and about. And that's where previews come in. Since they are jpegs, they don't eat much space on the MBP's HD. Well, that's the idea at least... I just can't get this to work. Now, the library is on the external HD. If I unplug that HD and launch Aperture, I have no images. None. And Aperture defaults back to my Pictures-folder. That's not what I want it to do. I want it to display the previews, while quietly ignoring the fact that the masters are not available. I have seen Apple tout this feature. So how do I make this work properly? Is the problem the fact that I'm using Aperture-managed library, and not referenced images? I'm not sure why that should be a problem. But if it is, how do I turn my one big Aperture-library in to bunch of managed files and folders? That said, I would rather let Aperture manage the library for me.