If you're using a tripod to take pics of stationary subjects, force it into 100 or 200 ISO and let it expose 5-10 seconds instead of 1/10 at 6400.
You're using high ISO inappropriately. You lose the dynamic range and color quality when you use a high ISO. It's great if you're shooting a show in a bar or you're a journalist. If the subject is moving, you've got no choice but to shoot it fast.
This was at ISO 6400 for 1/6 sec, handheld. This is a very high quality picture relative to the alternative of blurry mess you'd get from hand holding the camera for 1.5 seconds at ISO 400.
Not as good looking, but very much usable. If it was shaky where i was taking the pics or the boats were moving, I don't have a choice.