ELECTROMAGNETIC FIELD (EMF) DETECTOR: These compact devices measure various frequencies of magnetic and electromagnetic fields. Spirits often feed off these fields and their presence disrupts them. EMF detectors can locate these disruptions and measure their intensity. These are usually cheap, especially over eBay. Everyone on your team should have one.
INFRARED (IR) THERMOMETER: Great at detecting cold spots or hot spots produced by the other side. Test this one before taking it into the field. If you use this device in an outdoor investigation, be aware of natural temperature fluctuations. Depending on the various functions that come with some of these brands, they can be expensive. If they can't be afforded, don't worry, they're not mandatory.
WIND CHIME: Why a wind chime? If you're conducting an indoor investigation, these are excellent for detecting spirit movement. Find one at a craft store (make sure it's very light), hang it in the hall or doorway of a haunted location and if the spirit passes, it will chime.
THERMAL CAMERA: In our opinion, this is probably one of the best tools you can have. It reads areas of intense cold and heat. No better way to locate a ghost.
35 MM CAMERA: Black and white or infrared film is favored among ghost hunters, but anything will do. Always use fresh, top quality film! 400 speed Kodak Gold is a good choice. Take more than one camera on an investigation and keep them loaded! Use a camera light meter as well. Instant Polaroid cameras and digital cameras are not a good idea as your photo would be "worthless" and "no good" to skeptics without a negative.
VIDEO CAMCORDERS: Although they usually only see what the naked eye sees, these are good to have if something manifests or makes its presence known to you.
NIGHT VISION EQUIPMENT: Prices on some items like this can really get up there, but they are excellent tools. Sometimes night vision cameras can detect visible orbs when the naked eye cannot.
NEGATIVE ION METER: Detects the level of ionization in the atmosphere that can sometimes be affected by the presence of spirits.
GEIGER COUNTER: Another device to measure spirit disturbances.
MOTION DETECTORS: These have been used by paranormal investigators for years and are surprisingly good at picking up movements from the great beyond.
TREMOLO METER: Used when interviewing witnesses. It measures stress levels in human voices and could be a factor in uncovering a hoax.
LAPTOP COMPUTER: Good for taking notes in the field.
RADIOS: We use a pair of hand-held radio walkie-talkies with morse code buttons and a pair of headset walkie-talkies. Those are preferable to hand-held as they free your hands to do your work.
SPOT LIGHTS: Great for scouting outdoor locations and setting up/taking down equipment at night. Also handy if you're working indoors after dark and the power goes out.
BASIC EQUIPMENT: Most of these are optional, but it's amazing how handy they can be: binoculars, business cards (with your name and contact information), notebooks and pens/pencils (for keeping individual logs of events or drawing a map of a location), two or three flashlights, tape recorder with external microphone and brand new blank tapes (don't use old tapes) Sound from old tape often bleeds into new recordings-BN, tape measure, white ball of string, scissors or pocket knife, wristwatch, drawing paper, compass (which is actually a good tool for measuring magnetic/electromagnetic disturbances), chalk, ziplock bags, cotton balls (for detecting movement in interior locations), area maps (if possible), label gun and lots of labels, twist ties or small, bendable clamps, talcum powder (for detecting movement), liquid level ruler (to measure slanted surfaces), Holy Cross, Holy Bible, or any other spiritual object to provide comfort and protection in evil spirits, First Aid kit, ID (police and ghost hunters don't mix), cash, lots of film, lots of batteries (spirits often drain batteries for energy), and a Phillips screwdriver for replacing batteries.