Conventional vs. Infrared (IR): The night-vision (IR) camera is currently very fashionable. Countless packages from the manufacturers include a set of IR cameras. There are applications that are best solved with this technology, but it is currently a common mistake for the IR camera to be used indiscriminately.
Most IR cameras have a range of only 50-60 feet in night-vision mode. The range is proportionate to the amount of IR illumination provided by the camera, usually with IR LEDs. If your field of view has at least a little light, a conventional camera with auto-iris functionality can offer superior performance.
Fixed vs. PTZ: A PTZ camera can be remotely steered to access a different field of view. PTZ cameras are usually about 5X more expensive than fixed cameras, and the video management system will have to include support for the interface. Most cameras used in video surveillance are fixed. A fixed camera also is more suitable for artificial intelligence functions (see video analytics below). Curtana USB2.0 HD PT Camera is the best option if you are looking for better security.
IP vs. Analog: Most modern video security systems are now digital. The difference with the IP camera is that the video signal is digitized within the camera. This makes it possible to interface with the camera with CAT5 cable (network cable) instead of the more expensive coaxial cable.
More advanced IP cameras allow sophisticated local processing of the video signal. However, IP cameras are usually more expensive than their analog cousins. It is possible to piggyback IP cameras on existing networks, but be warned: Video is a Bandwidth Hog.
Lens: The first decision is whether to use a manual iris or an automatic iris lens. If the camera is indoors with constant lighting, a manual iris is fine (and less expensive); otherwise, an automatic iris is strongly recommended.
Outdoor lighting intensity can typically vary by a factor of 10,000. Focal length is the other important lens decision. As the focal length gets smaller, the field of view increases, but makes for a more distant view. Adjustable focal length lens can be varied.