Lumolab noise test chart for Pentax K-7 at 2900°K and ISO 100.
This photo was underexposed by 5 stops! In order to make the resulting (almost black) photo visible within an 8-Bit file format as allowed by SmugMug, I pushed exposure +5EV before saving as JPG. The result is seen above and theoretically, corresponds to ISO 3,200.
This photo is from a different session using the identical camera and same light source as before. The slight variation in exposure is from the setup of light.