Keep the noise down
Joe says… Frank was using Auto ISO to take his shots, and relying on the camera to adjust the exposure. However, in night-time photography chroma noise appears first in the dark areas of the photo, which is exacerbated by higher ISOs. This is why I told Frank to switch off Auto ISO. He was using a tripod, which kept the camera still enough that he could use a long shutter speed to expose the shot rather than bump up the ISO.