I decided that I would do an experiment because I normally go with the three shots. I should state that when I use HDR I am trying to make a landscape picture that captures a fuller range of the values that the human eye sees, not what could be considered an image with unreal colors.
So I went up into Big Cottonwood Canyon here in Salt Lake and stopped at Storm Mountain. That is a beautiful rugged area, although it is prettier in the summer than it is in the winter. It was about 6pm at night. I took the following exposures.
-4 EC 1/3000s F/11
-3 EC 1/1500s F/11
-2 EC 1/750s F/11
-1 EC 1/350s F/11
0 EC 1/180s F/11
+1 EC 1/90s F/11
+2 EC 1/45s F/11
+3 EC 1/20s F/11
+4 EC 1/10s F/11
These were taken by setting my bracketing to three frames, 1 f/stop apart. I then set my exposure compensation to -3 and took the -4, -3, and -2 shots. I then set exposure compensation to 0 and took the -1, 0, and +1 shots. Exposure compensation was then set to +3 and shots +2, +3, and +4 were taken.
I then produced three images using the software package Essential HDR Standard Edition.
The first image contains all nine shots.
The second image has three shots with each of them being 1 f/stop apart. The middle shot has an exposure compensation of +0.
The third image has three shots with each of them being 2 f/stops apart. The middle shot has an exposure compensation of +0.
The fourth image has three shots with each of them being 3 f/stops apart. The middle shot has an exposure compensation of +0.
Although I think that the thee shot with one f/stop difference is acceptable, the nine shot appears to have more detail to it. So if you have the time and can make sure you don't change the position of your camera, the nine shots will most likely give you a better image.
I think that this image is not a real good image to have done the test with. I'll have to try a different subject sometime.
