I photographed someone on a blackground using Provia 100 with studio lights. Since I planned on rewinding the film and creating a second image over the first, I set my film speed to 200. The lights were set at 5.6 but I forgot to change my aperture and I shot at f/11. The base image is now 3 stops underexposed. I still want to create multiple exposures over my subject, but I'm not sure what I should set my camera at.