There have been several posts about ISO but I have not found this specific question.   On Red's website they state: "For most scenes and uses, exposing with an ISO of 640-2000 strikes the best balance between highlight protection and low image noise."   I have found that shooting at 800 on the Red Epic MX with the Redcode at 8:1, the image has a significant amount of noise in a dark scene.   So, I'm wondering, does changing the ISO to 640 or 500 really make much of difference in the noise