Have you actually tried to edit and export a deleted image? All you are working on is the small preview that Lightroom has generated. If you try to export that image you are going to get a message that the file cannot be found. And if you go to the develop module there should be a message in the main editing screen indicating that the file is missing. You can't do anything productive with the Lightroom preview file. It's just a small preview. Nice try, but it isn't going to work. And, no, it isn't true that Lightroom keeps all of your DNG images. If you delete your DNG files, they are gone. End of story.
Ahhh, I get it. A full image should be (from my Canon Rebel and how it is currently set) 17x11, 300 res.
If I delete that image from my hard drive, then edit it in Lightroom, and then Export it as a jpg, the image comes in at 8x5, 300 res. So that would be the largest file you can get from using a Preview image.
I am glad to have it verified that it is necessary to keep the original .dng file in a location on my hard drive.
1 person found this helpful
I think you'll find that if the original file is gone and you're trying to work with the preview only, you won't be able to do any editing and develop module and all of your export options aren't going to be available. The preview really isn't any value to you by itself.