How far away can we see things using a long range PTZ camera? Obviously, we can see the moon which is 238,900 miles away, but of course we would need a powerful telescope to see the small craters. We can see people in a crowd, but when we want to identify their face, it gets a lot harder. The distance is determined by what detail we need to see.
Do you want to be able to detect a vehicle moving, or identify the person driving the vehicle? The objective will determine the type of IP camera system you will need. In general the distance is determined by the lens, the type of camera (thermal camera or optical camera), the camera resolution, and sometimes the IR illuminator available. This article describes how we can specify the IP camera system required for long distance viewing.