Aperture 3

I believe it saves an edited photo as its own file. So the original file will be left intact, but you will have a separate file that you can use as the "original overwritten with changes". You may be able to go into the library and delete the original intact file and just keep the edited file as the only file, thus making it a new "original". This is how iPhoto works, I think Aperture follows the same method.

 

I haven't got Aperture, but am interested in it.

One of the reasons I am is because I think you are wrong there. You are correct that that is how iPhoto does it (I think), but from what I understand, Aperture does it differently.

If I'm right, Aperture stores the original file, and then just notes any adjustments that you make to it so it saves having to have multiple copies of the picture, like iPhoto does, and keeps the size of the library down.

As a result, you could have a number of versions of your photo's in your library (i.e. a black and white copy of them all if that's a possible adjustment), and ones that are all adjusted in other ways, without your file size bloating.

As an example, say you have a library full of portrait pictures that all suffer from Red Eye, and you correct them all. iPhoto will have two copies of each picture, but Aperture will just have the original and a note of the changes, which it uses to create the corrected version ad hoc.

Perhaps someone could correct me if I'm wrong.

EDIT: It looks as if I'm on the right lines. From the Apple Website:

Multiple versions of a photo. Minimal hard drive space.
When you want to create an alternate version of a photo, iPhoto duplicates the photo. Aperture stores as many variations as you want in a single image file. That’s big news, because it eats up far less hard drive space than storing duplicate photos. Aperture makes it easy to keep track of all those versions, too, so you can use different ones for different projects.

 

Answering the other questions:

Yeah, that's one of the two ways you can do it. The two ways are with "managed files" and "referenced files". Google "aperture referenced files" and read up on that way, as that's what you're asking about.

Yes if you used managed files, no if you use referenced files.

In either mode, you generally wouldn't use the original file in any way, as the original file is exactly that - the original, unmodified master file.

What you'll probably want is to export a new version that contains any changes you've made. When you export a file, it creates a new file you can then upload to a site. I usually then delete the exported file. If I need it again, I can always re-export, but I rarely need to.

However, if in either mode, if you haven't made adjustments to the original, you could access the original file and upload that if you really wanted to.

 

You CAN work from files on an external if you want. I saved my Aperture library on my external, and recently re-formatted. I could click on my Aperture Library and it would bring up what I had backed up. It asks you what library you want to open (if you have none on your internal HDD).

Personally, I like how A3 organizes my shiest; but that is just me. My library is like 30Gigs, so i could see why people would want to work from an external..