@blake I got the non-POE version from that Amazon link, it comes with a 12V 2A adaptor. I may have spoken too soon- during the day it worked fine. At night, the image is too bright (gain up full) so all plates are completely washed out. There are several exposure settings in the MSIE browser plugin that worked during the day, but they have no effect in night mode (!?)
Below are three images from the Sunba 507-20XB (2 MP white 20x PTZ), all at max zoom (f= 94mm). The camera looks towards a T intersection which is 330 feet away, the yellow house beyond is at 450 feet. First image during the day, second at night without a car, third with a car driving away. Clearly, not too useful at night, unless I can adjust the gain down somehow. Also the full-time autofocus tries to resolve the big fuzzy taillights / headlights and makes things worse.
Having a quick scan through the 507-20XB thread
here (I should have done before buying!) I have a sinking feeling that the camera is simply unsuitable for LPR use. It looks like the gain can not be adjusted down.