Thanks for the replies. I appreciate the help, though I'm not happy to hear the truth about the "autofocus" feature of the camera/lens combination. Coming from the photography world where I've seen focusing technology continually improve over the last few decades, I'm well aware of what is possible with current tech. Larger apertures and longer focal lengths make depth of field smaller and autofocus more difficult, especially in low light, but not impossible even with moving subjects. My digital still camera (5+ year old Canon 7d) focuses a 500mm lens quickly enough to reliably lock focus on moving wildlife (birds flying, ground animals running) at dusk. My Dahua PTZs do a much better job of autofocusing stationary objects at all focal lengths, even in low light, than the DH-IPC-HFW5241E-Z12E.
From what I'm hearing, I guess I'm going to have to drastically lower my expectations and accept the reality that the DH-IPC-HFW5241E-Z12E "autofocus" has serious flaws (hardware or firmware limitations) and that in order to make use of the camera successfully for LPR and/or other purposes, some form of a manually focused, fixed focal length work around is usually necessary. Disappointing.
I've played around with different scenes and focal lengths some more. In my case as well, the longer the focal length, the worse the autofocusing. When I zoom in or out while in autofocus, the camera focuses such that the foreground is consistently better focused than the background, but nowhere in good focus. I have to manually move the point of focus farther away to get anything in focus. In the photography world, this would be called (severe) front focusing. My still camera has a feature that allows me to calibrate the camera for a particular camera/lens combination in order to eliminate front (and back) focusing. I suspect my copy of the DH-IPC-HFW5241E-Z12E could be made to perform better judging by others' comments that they have some success with autofocus which, unfortunately, hasn't been my experience. Has anyone ever heard of improving a security camera's autofocusing capability by way of being serviced by the manufacturer?
Thanks again for the help.