There are various types of equipment used by paranormal investigators and I’ll give a brief overview just to give you an idea on how elaborate these ghost hunters can get. As with anything, some people are more skilled in technique than others. Anyone can go onto Amazon and buy this stuff. Some of these devices are highly sensitive electronics designed to measure slight changes in the electromagnetic field or air temperature. The usefulness of this equipment is directly proportional to the scientific competency of the person operating it.
Cameras: Film, Digital, Infrared, 3-D, Thermal Imaging, Video. The disadvantage of digital over film cameras is that digital does not produce a negative so if the photograph wants to be enlarged, the picture loses resolution. But digital cameras can take numerous pictures quickly without having to change film.
3-D captures images from different angles, giving the three dimensional appearance. These photos are not easy to fake.
Infrared is used under the theory that spiritual energies may exist in an invisible light range. In the same way Thermal imaging cameras pick up heat signatures thought caused by ghosts.
Audio recording: Sound recording of ghosts are called electronic voice phenomenon (EVPs). An old fashioned tape recorder or digital recorder can be used to pick up scratching, rapping, voices or moans. The recorder is usually left in a room running then listened to much later.
EMF Meter: electro-magnetic field meter. The theory is that a ghost has energy output and, if present, will alter the reading on the meter.
Ion Counter: There’s another theory that ghosts are contain highly charged ions which can be detected by the ion counter.
Motion Detectors and Thermometers: “Cold spots” are supposedly a sign of the ghostly presence, therefore, a sudden drop in temperature would be useful for an investigator to recognize a possible event. Same goes for the motion detector. Motion might detect poltergeist activity.
Night Vision Goggles: A ghost hunter’s personal equipment device. Whether that helps them see the ghosts better or just see better in the dark, I don’t know.
I wanted to recommend THE CASE FOR GHOSTS, An Objective Look at the Paranormal by J. Allan Danelek. I found a lot of information in his book for these blog posts. And also at the various Paranormal Societies of Pennsylvania.
Eastern Pennsylvania Paranormal Investigations http://www.eppsinvestigations.com/