I am using 6 lamps to light this set which is actually quiet dark. When shooting stop motion it is a good idea to use long exposures in order to help eliminated flicker.For this reason, I try to keep my ISO at about 100, my aperture between f/4 and f/5.6 and my shutter speed at 1 sec.
If I need to adjust the exposure I well increase or decrease my ISO setting but leave the other two fixed. If I need greater depth of field I will close down my aperture to f/11 and adjust my shutter speed to an even longer exposure. I like the deep blacks that I get by keeping my ISO low. One last but very important note, I use fixed or hard lenses with my camera.
Digital lenses communicate with the camera between frames which can lead to slight variations in exposure. This can occur even when you have set the lens to manual control. Any variation in exposure will lead to flicker. Because fixed lenses do not communicate with the camera and are essentially manual lenses, that problem is eliminated. All this my sound very technical and uninteresting but it is essential. As much as we'd like it to be just about the animation, working in stop motion requires an understanding of many disciplines in order to produce professional looking results.