I have an entrance that have some low light concerns. We are not talking dark, just challenging enough to make shutter speed an issue. People are generally passing inn trough the entrance at walking pace, trough a depth of field at about 6 meters from the camera, and often passing underneath the camera. Because of the lighting situation the iris is practically always fully open, and consequently the depth of field is pretty short. The entrance opens into a large room, so the depth of field needs to stay where it is. I have been nagging the higher powers for some more light, but get a pretty harsh no, for customer comfort reasons.
I have been setting the shutter speed at 1/100s-1/125s because of what I perceive as motion blur. If people are moving at at a "determined" pace, and with the head swinging, I get blurry faces at 1/30s and 1/50s. I have set gain and iris to suit the light coming from the faces, not the area behind the faces. What happens in overexposed or underexposed areas is of no interest, as the camera is dedicated for the task of capturing identifiable faces. I have turned off wdr because it just made the overexposed areas outside visible. I imagine this would leave less “greytones” for the face. I also noticed image distortions that I have decided must be the result of dual exposures. I have turned blc on and off without seeing any significant improvement. And when it got dark outside, blc apparently confused the automatic gain control. So I turned it off.
The problem I get, with these settings, is that I get very little contrast in the faces. Even with ppm at 250+, eyes become dark pits, blonde eyebrows disappear, and the faces get so smoothed out that it is difficult to determine the shape of the nose and chin. I have set bitrate to max, quality to max, and even reduced frame rate to get more bits/image. The camera uses h264 for compression. Sometimes I get maybe one or two usable images, but often I get none.
I have intentionally left out make and model of the camera, because I have tried different cameras, and because I hope for more general answers to the following questions.
I was wondering what other people use for shutter speeds in these situations? Am I too mental about the shutter speed? And have I made any obvious errors in my setup?