Hi Shankar,
But I keep getting a plot with colorbar ranging between (1e-31,1e-28). I can't see what I am missing.
This is a bug. Inserting the line
p.set_autoscale(False)
above the set_zlim line fixes it. I've been trying to track down the right way to fix this bug for some time, and you can see the results of this so far in the mercurial repository in the named branch "plotting-refactor". I've committed a hotfix that will execute this fix inside set_zlim in revision 1553 to both 1.5 and trunk.
Please let us know if this works for you,
Matt