Choosing a Distance Camera

Sony RX-570 Network IP Camera
 with 36X Optical Zoom

The ability to create a camera that can see at a long distance can be very tricky. A good distance camera is usually a result of a good lens and not the camera. There are two factors that can play directly into the distance that a camera can shoot, the optical zoom and resolution of the camera sensor. Optical zoom will allow you to see objects without distortion of the images. The more that you zoom in will also make the camera more susceptible to vibration which can cause a blurry picture.
High-End zoom lens's for SLR cameras will usually have some sort of image stabilization built in to counteract the effects of vibration. If money is not an object then a (Canon EF Telephoto lens - 600 mm - F/4.0) is a great place to start. But it will start at around $8000.
There are also IP network camera's from companies such as AXIS and Sony which can act as great distance cameras. The Sony RX-570 has and optical zoom of 36x. The AXIS 233D has 35x.
Another thing to consider is that HD Pan/Tilt/Zoom cameras are starting to hit the market and work very well also. The AXIS 5534 HD PTZ has an 18x optical zoom, but due to the HD picture it is as effective as a 36x camera.