I am getting a lot of noise when shooting indoor portraits with my D5100. Not sure why as I am shooting using an umbrella with 500w daylight balanced constant light quite close to my subjects. I am also quite close to the subjects. I am not using any Speedlight or flash. I am trying to keep the ISO as low as I can at 800, so I'm not sure why there's SO MUCH noise. It is really a lot! I only have a kit lens, but I open it up as much as I can. What am I doing wrong?
Thanks so much for your help.