This spring I’m teaching a freshman-level Digital Capture Processing class at my old alma mater, and this week’s assignment was to create an HDR image. Of course one of the assignment requirements is that the dynamic range of the scene you’re photographing must exceed that of your camera’s sensor.
As the students tried various things, it became apparent that this assignment was going to be a much bigger challenge than it first appeared. One of the problems they were encountering was that the dynamic range of many cameras is now so great that fairly high contrast scenes fit comfortably within that range without clipping.
Driving up to the little guest house that I am fortunate enough to stay in when I am in the area, I was struggling to figure out a way to illustrate how easy it is to find such a scene. It was twilight when I arrived and the owners had turned on the outside lights. I immediately saw my opportunity, grabbed my tripod and jumped out to get the shot before the light faded.
True, this was a super-high dynamic range scene, with the lights on the porch easily exceeding the shadow detail by 14 stops or more. But twilight was essentially solving the dynamic range problem, and bringing up the outside with a modest bump on Exposure, and pulling down the Highlights gave me a perfectly acceptable image without the need to use any special software. Sure, where the lights hit the wall it does burn out a bit. But the overall effect was still natural enough to not require jumping through any special hoops.
It was when I woke up early the next morning that I found something completely different. I was leaving before dawn, and an almost full moon was shining right onto the front of the guest house. I had turned off the porch lights, but the inside lights were still on, and this is roughly how the scene appeared to my eye in the moonlight:
Increasing the exposure to 30 seconds in-camera, gave me this:
Turning on the outside lights, and exposing for them gave me this:
Then with a little Highlight correction and minor retouching, layering the two together in Photoshop by simply using the Lighten blending mode gave me this:
The results reminded me once again, that thinking through the problem and careful camera work always leads me to a more interesting (more realistic? :-) result than anything I could have achieved using an out-of-the-can HDR solution.
The whole exercise also reminded me of the girations we used to have to go through to create a good “composite” in the film days. I photographed this short-lived restaurant for Interior Design magazine back in 1982, and it required several exposure tests at various times to find the right balance. In the end it was all put together on one piece of 4×5 Ektachrome with three exposures: one for the sky at twilight, one for the exterior lights a bit later, and one for the interior lights even later, once it was completely dark outside.