To get the best performance from your camera, the rope or string lights generally work better than just one bulb. The beauty of them is that you can use them to distribute the light more evenly around the stall. That gives you two advantages, one is that the camera doesn't see a 'hot spot' of light. The camera's iris tries to give a balanced image. It will adjust based on the amount of light it sees. If there is one area that is really bright, it will close its iris down so the bright spot isn't glaringly bright. When it does that, it makes the darker places even darkers. For example, if the light is in the middle of the stall, the center is easy to see, but the corners may be too dark and look black. With a rope or string of lights, you can put them around the stall including in the corners and avoid having any areas that are significantly brighter. This means the camera sees all areas of the stall equally well.
The second advantage to distributing the light, is that is cuts down on shadows. A single bright source of light will cast a shadow. If the stall is circled by lights, then all sides are equally lit, so you don't get the shadows. And, as myself and many others can tell you, shadows can become all kinds of things (including foals) when you are sleep deprived during mare stare!!!
Another note... when you are putting up your lights, take care to know what the camera is seeing. You don't want to have the camera looking directed at ANY light source, even a small Christmas tree bulb. Again, it is a 'hot spot' and if the camera is seeing it directly, then it will shut down its iris to try to even out the light levels and will make the whole picture darker.
