You may need to cover your PTZ's trouble spot with a Static cam. 
I learned from the forum and hands on experience, that my camera setup for a 75 unit Condo, was best served by static cams. 
My first IP cam was a PTZ, eventually put out to pasture in the Back lot as a stationary camera. 
I began with what they left me, 9 black white cameras that looked like the 1st pic below... with no view of the outside of the  property.
Then I began by trying to upgrade the existing cams ( when i had time) but this still left the crappy experience of reviewing video on some locked down software called EYEMAX on a PC with a whopping 2GB of memory. 
Hit the Google search and wound up here. 
got just enough information to put together a rudimentary Ip cam setup, But I didn't really know what I was getting into.
1st cam was a PTZ, looking outside at the front parking lot. A pinch point where all the " car checkers" had to cruise by to go into the Back Lot.
I gave me data, but not enough data. 
I soon realized " i need a lot more cameras". 
then came the Cisco POE switch and a BI PC, and started pulling cable runs.
 Then my underground garage shots changed from pic1 to Pic 2. 
eventually wound up with about 17-18 Ip cams 
and the PTZ was demoted to Static cam over watch of the rear parking lot. 
the last pic was with 17 cams. ( and 9 more on analog CCTV system) 
total was eventually 28. 
