Camera roll when using Damped Track

Hi,

When I use Damped Track constraint on a camera, the camera always tilts over to it’s side in seemingly random ways. Can anyone tell me how to use Damped Track on a camera whilst keeping the camera’s roll flat to the floor? Thanks.

Aha, it seems ‘Track To’ is the constraint to use! Can anyone tell me the difference between ‘Track To’ and ‘Damped Track’ though, please?

The Track To constraint applies rotations to its owner, so that it always points a given “To” axis towards its target, with another “Up” axis permanently maintained as much aligned with the global Z axis (by default) as possible.

http://wiki.blender.org/index.php/Doc:2.6/Manual/Constraints/Tracking/Track_To

The Damped Track constraint constrains one local axis of the owner to always point towards Target.

http://wiki.blender.org/index.php/Doc:2.6/Manual/Constraints/Tracking/Damped_Track

In other words, Damped Track doesn’t care much about the tracker’s orientation except on the single local axis that is pointing at the target. Track To points at the target and maintains a mostly upright local orientation.

Thanks. SO now I understand what each does, but still unsure as to the logic that the tilting of a Damped Track tilts by. Why would you ever use a Damped Track in preference to a Track To?