I have a MacBook Pro (late 2011 model) that originally shipped with OS X Lion
I have updated it through the App Store to OS X Mountain Lion.
As I've understood from other discussions and support site, I should be able to restore to exactly how it came from the factory.
So, this is what I did so far (aside from backing up whatever I cared about on that machines's hard disk)
1) Restarted the machine to Recovery (command R)
2) From there, selected "Disk Utility" and erased/ reformated the "Macintosh HD" partition, as per instructions (Mac OS Extended).
On that step, it also shows a "disk1" disk image, with a 1.3 GB "Mac OS X Base System" partition. I didn't touch that. I am assumng it is the factory image, presumably with OS X Lion, that I want to reinstall the OS from.
3) Quit "Disk Utility"
4) Start "Reinstall OS X"
My problem - after step 4), the OS X reinstall utility only offers me to reinstall Mountain Lion over the network. And, after validating online with Apple and collecting my Apple ID credentials, it starts doing that. I have not gone through the conclusion (it's > 1 hour download) but I suspect at the end of it it will have Mountain Lion installed.
This is not what I want - I want to see if I can get it back to OS X Lion and solve an external display problem my online research on the forums suggest is Mountain Lion specific.
I was expecting to be able to do that by restoring the computer to factory image (which, again, I assume is that disk image on the hard disk). The online instructions for the "Reinstall OS X" are very vague ("follow the prompts", basically, and the prompts only ask my Apple ID for the Mountain Lion download). So I have not been able to coerce it to consider the image on the hard disk as the source for the reinstall