Other Equipment
35mm Camera- Nothing fancy with at least 400 speed film. 800 speed film is also good at night but you'll have to test your cameras flash strength to see which speed works best for you. Even those single use 35mm cameras have gotten good results. If you are more experienced photographer you may want to try infrared film. I have seen results from Polaroids but I suggest you only use these along with a 35 mm camera so you can compare the results. I have used Fuji film primarily but I have also used Kodak and a department store brands with similar results. When you develop them you don't need to go to a camera shop, the local drug store or department store is fine. Let them know you want all the pictures developed so that you get the pictures that they might think are bad ones. These "bad ones" are normally your best ectoplasm mist photos.
Digital Camera - Regardless of what you've heard digital cameras are great tools for ghost researchers. Once upon a time they had their limitations and problems but that is no longer the case. Not only do they allow you to see instantly if you have a positive photo, they can also take photos in limited infrared range of light.
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Flashlight w/ spare batteries - a common sense item. Remember to bring spare batteries for everything. Due to spirit activity, batteries often run down very fast and you don't want to miss anything because of dead batteries. I recommend using a red lens flash light to help preserve your night vision.
First aid kit - just in case, it's very easy to trip in the dark and get cut.
Notebook w/ pens and pencils- you need to write and log in everything that happens. If you don't then you really don't have much research information. An example of this is one investigator gets a EMF reading that's high and never writes it down. Another investigator takes a picture of the same area but is not aware of the reading and gets a anomalous image. Without that EMF reading the picture may be good evidence, but with a report noting the reading, the picture greatly increases in evidence value. Many investigators use a pocket tape recorder in stead and that is fine, just make sure you have spare batteries and tapes.
Jackets or weather appropriate clothes - if you are cold you are not at your best and your observation skill could suffer, pretty common sense.
Watch - so you can log in the times of events and your arrival and departure.
Advanced and Optional
Video camera (optional tripod) - Video cameras are an important instrument for an investigation. Unlike still cameras they provide us with constant visual and audio surveillance for review and observation. The video cameras we use are equipped with infrared capability and this is the mode we use. With video any phenomena occurring can be documented in its entirety. This will show the length of time the phenomena occurs, what is happening, the conditions surrounding the phenomena, and possibly even the cause of the phenomena.. The Sony line of camcorders has an infrared night shot feature that enables you to video tape in complete darkness and see beyond what the human eye can see. You can use these on tripods or walk around with them. You should also invest in an infrared light extender which will help your camera see in the darkest places and make the quality of the video better.
Cellular phone - if you have one it can come in handy in case of an emergency.
A Compass - it's a useful instrument to an investigator due to its compact size and low cost price. When used on an investigation this will indicate spirit presence when the needle cannot come to a precise heading or spins/moves erratically. This works on the same principle as a EMF meter.
Candles & matches - batteries often run low during hunts so you may run out of them and still need a light source. Another good idea is a camping lantern that runs on lamp oil. Be careful using the candles around motion detectors, they will set them off.
Motion Detectors - these can be used to sense movements by often unseen forces or spirits. You can get battery operated ones for about 20 dollars and they are great for inside but I have seen them used successfully outdoors as well, just watch the placement. You don't want a tree branch setting it off.
Hand Held Radios - Or Walkie Talkies are very useful in a large outdoor area and a building with groups spread out in various rooms. They could be great in emergency situations or just to rotate groups. Be sure to be aware they could interfere with your EVP recording though.