From experience, no way are the DORI numbers accurate, especially for night. Those numbers are based on a static image. As I mentioned, the more zoom, the more light is needed. You can cut that number by 75% or more unless all you are looking at is static images. Once you set the shutter such that you eliminate motion/blur and ghosting, the effective distance is cut a lot. And 8MP on a 1/2.8" sensor will be blind at distance.
At night, my 2MP version of the camera beats the 4MP version at distance. Not even close. And in the daytime, I can read plates from 900 feet away with my 2MP.
If I had it all over to do again, I wouldn't have bought the 4MP on the 1/2.8" sensor. The 2MP on 1/2.8" sensor is the ideal MP/sensor ratio.
Are you trying to pickup plates (LPR) at night of a moving vehicle or parked?
You will find that one camera cannot be the do all/see all.
Regarding a camera for plates (
LPR) - keep in mind that this is a camera dedicated to plates and not an overview camera also. It is as much an art as it is a science. You will need two cameras. For LPR we need to zoom in tight to make the plate as large as possible. For most of us, all you see is the not much more than a vehicle in the entire frame. Now maybe in the right location during the day it might be able to see some other things, but not at night.
At night, we have to run a very fast shutter speed (1/2,000) and in B/W with IR and the image will be black. All you will see are head/tail lights and the plate. Some people can get away with color if they have enough street lights, but most of us cannot. Here is a representative sample of plates I get at night of vehicles traveling about 45MPH at 175 feet from my 2MP camera (that is all that is needed for plates):
PTZs are problematic for LPR because you cannot force a focus like you can the fixed cams, meaning that at the shutter speeds needed to read plates, because the image is dark, the PTZ is always hunting for something to focus on, and then the car comes by and it is in the middle of focusing. You can do tricks like putting reflective tape out there, but then at night that PTZ is essentially a fixed cam.
Most PTZs are more difficult to set a manual focus that sticks. So you end up having to force it to a field of view while enough light out to get the focus, but if you move the PTZ at night and then back, it will be blurry for plates the rest of the night. Most that have tried to use PTZ here have gone to a dedicated cam for LPR purposes. The camera will only be seeing about the size of the car and not much else.
It is almost a waste of a PTZ to use it for plates. The 5241-Z12E at half the price or more would be a better option and can get plates at 200 feet or so.