I recently upgraded from iPhoto to Aperture, partly motivated by the fact that it would allow me to better manage my library. I started shooting RAW last year and am quickly running out of space on my internal hard drive. My understanding was that Aperture would allow me to keep the RAW files on an external drive, while keeping a local JPG - I've learned that Aperture calls this JPG a preview file. What I didn't realize though, and what is really surprising to me, is that it seems like you're actually fairly limited in terms of what you can do with this preview. Sure you can view all your photos, and depending on your settings for previews, you can view it at full resolution. But I was surprised to see that you can't export or share photos unless your external drive with the master files is connected. This doesn't make sense to me - if the preview file lets you see the photo at full resolution without the external drive with the master files connected, doesn't that mean your internal hard drive contains a jpg copy of the photo, and if so, shouldn't that be good enough for sharing to Facebook, or dragging and dropping the preview onto the desktop for a JPG file? Meanwhile, it does seem to allow you to share with iLife and iWork projects without the original, but sharing the photos over facebook or email is about 99% of what I want to do with my photos, aside from working on the originals. Am I missing something here?