Straight Shooter wrote:
You have lots of good advice there. Here's my $0.02. For best results, use a solid tripod with gimbal head, f8-11, fast shutter speed (at least 1/500th), don't be afraid to increase ISO (your 6D can handle that), use remote shutter release or in-camera shutter delay (if the subject is stationary), and try not to zoom over 450mm, but you can get not so bad results at 500mm if you are ulta-careful.
I suspect gimbals can be more stable with a long heavy lens because they allow you to balance the camera.