At my recent exhibit at the Harrison's home, I got so many questions on this print (for some of which I couldn't even remember the answer) that I decided to post a history of the image here.
1. First shot, direct from the camera in RAW (.CR2) format. Canon 5DmkII, 24-105mm f/4L lens at 24mm, ISO 100, manual mode. This was the "normal" metered exposure, 3.2 sec. at f/14 for depth of field even with the short lens.
Even before looking at the histogram, it was obvious that the highlights would be blown out and the shadows blocked. Most lighting was from the skylights above; the shed door in front of this engine was closed and the only other sources were an open door to my back left and the reflected light from the Santa Fe diesel. So keeping the aperture constant, I took four more shots at +1, +2, -1, and -2 stops of exposure time (obviously with a tripod).
Visually, this is...well, a museum, and a working museum at that. My lifelong fascination with trains has always been pretty visceral, and although there's good raw material here (pun intended), this "tourist" image just doesn't convey what I feel about the subject.