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.
At 100:
At 3200:
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.