viewpoint roll / pitch

[exhale]

hello,

when i added these instructions to
my script, it looked as if the viewpoint
is always a bit pitched / rolled.
Is there a way to resolve this?
(i copied the values of the translate
from a viewpoint.get)
The problem arises @ translate()
removing lookat() does not seem to
affect the roll / pitch

view = viz.get(viz.MAIN_VIEWPOINT)
view.translate(-6.2,1.8234411478,16.9)
view.lookat(17,0,20)

thanks in advance,

Kevin