Selecting an Infrared Camera
by Joe Wetterling
Whether hard-line or wireless, there are many options to consider when purchasing a digital camera for any application. Many security cameras seem to "fit the bill", as they offer nightvision as well as small, lightweight housings. Its important to remember, though, that no infrared camera was built specifically for paranormal investigation, so its important to know what are the most important factors for that application.
Output
If you plan to connect your camera to a standard VCR or DVD recorder, then your camera will need to use RCA connectors. These are the standard red/yellow/white connectors found on TV's, VCR's, and other home entertainment equipment.
A number of security cameras use BNC (Bayonet Neill-Concelman) connectors instead. These professional/commercial video connectors are intended to hook the camera up to specialized viewing or recording equipment. Converters do exist, but be sure you can obtain one before you purchase a BNC-connecting camera.
Sensor
There are two types of sensors commonly used to capture digital images. CMOS sensors use the same integrated circuits manufactured for computers and other electronics. They draw little energy and are less costly to manufacture than the alternative. CCD (Charge-Coupled Device) sensors are produced specifically for digital photography and similar applications. They require considerably more power and are more costly than CMOS sensors.
While CMOS sensors are improving in image quality, CCD sensors still surpass them and are the better choice in most cases. A CMOS sensor would be ideal only where electricity was unavailable and sufficient battery power would be a concern.
Resolution
Resolution refers to the quality of the image produced by a camera. It can be presented as pixel area or a number of TV lines.
A pixel is the smallest unit in a digital image - a "picture unit" or one dot in the total image. The quantity of pixels, which I'll call pixel area, is given in two numbers, width x height. An image 512 by 492 pixels is comprised of 492 rows of 512 pixels each. In short, the greater the pixel area, the more detail there is in the image. Greater detail yields a sharper image and one that can be enlarged farther without a loss of detail.
TV lines (or scanlines) is a similar concept - the number of lines of pixels that make up the image. Like in the case of pixel count, the greater the number of lines, the more detail will be available in the image.
IR Performance
IR Cameras generally use infrared LEDs to operate in total darkness. LEDs vary in quantity, of course, but also in wattage. (I have a camera with three IR LEDs, for example, that outperforms another with six.) I have never seen the wattage of LEDs included in a camera's published specifications, so we will need to rely on descriptions of effective range.
Of course, you can conduct your own effective range tests if you have a sufficiently dark, long area in which to work. I employ a very simple but effective method - walking away from the camera with a tape measure, calling out each foot. As I review that recording, I can see and hear how well the camera performs at each distance and how far I can reasonably expect to see with it.