Here’s a side-by-side, to show what it looks like when you walk into an unlit tunnel in the mine, and look back.  Same target for the photo each time; one’s just farther away by maybe 50 feet. View high resolution

Here’s a side-by-side, to show what it looks like when you walk into an unlit tunnel in the mine, and look back.  Same target for the photo each time; one’s just farther away by maybe 50 feet.