It looks like the NEW Dahua 2019 Catalog explains things a bit more.
The Lite 2.0 Series specs show the 2831T as 3.7-11mm varifocal only,
while the 2531T, 2431T and 2231T have the 2.7-13.5mm lens
The 1831 seems to be no more
What I would like Andy to ask Dahua is
1. Is the 2831T version 1...