As far as I know SecondLocator() is the smallest it gets for time-date plotting in matplotlib. Probably a new class needs to be written for MilliSecondLocator() in dates.py
Alternatively, you might use just floating-point version of your time values and with a little adjustment (Ryan mentioned this in the recently, and will forward there for other suggestions) millisecond resolutions should be visible when zoomed in furthest.
sci_fmt = plt.FormatStrFormatter("%.2f")
By the way, where did you get mpl v1.1.0? Mine says:
On Wed, Mar 24, 2010 at 1:25 PM, Tom Kuiper <kuiper@…3039…> wrote:
I have some time tagged data spanning about three minutes with 4 ms
resolution. If I plot these with plot_data and focus in on some event
at high resolution I lose the tick marks. It seems that the minimum
tick spacing is 1 sec. That appears consistent with strftime which does
not provide for fractional seconds.
I thought I saw this issue go by not long ago but I don’t recall the
solution, if any.
I’m using python 2.5.2 and matplotlib 1.1.0.
Thanks and regards,