Dallas Ft. Worth - Washington D.C. - Seattle - New Orleans
For temperature measuring, I like this little Indoor/Outdoor Thermometer from Radio Shack; part # 63-1023 for about $15. It measures in tenths of a degree, has fairly fast response, seems accurate, and has an EL backlight.
You can also get digital combination weather meters such as this Extech Hygro-Thermometer model with clock which measures both temperature and humidity.
One of the more popular devices out there is the IR thermal scanner. This is a temperature measuring device which works by sending out a thermal beam and measuring the emissivity of a surface. This is to check for or verify unusual cold or hot spots in a room. While it could work in theory for this purpose, there has been some debate about whether a ghost or paranormally induced thermal variation would have enough mass to shift the reading.
Nonetheless, many hunters swear by this device and it is usually one of the second pieces of analysis gear purchased after an EMF meter. Prices range from $40 for the miniature model sold by Radio Shack to over $1000 for high end offerings like the MX Ranger series.
There are a number of features to consider when buying one:
1) Range – many of the cheaper ones may only work out to 15 feet or so; too short for any but the smallest rooms.
2) Spot ratio – this is a spec which describes how large the sampling spot is in proportion to the measuring distance. The low end models are rated at 6:1, which means that at a distance of 6 feet, the cone of the beam is 1 foot in diameter. Better ones are at 8:1 or more, while at the very top end it is not unusual to see 60:1 +
3) Temperature resolution – this describes the decimal rounding characteristic of the scanner and helps a lot with detecting small changes. Unless otherwise noted, most lower end and even mid range scanners measure to the nearest degree in Fahrenheit, while slightly better ones measure in increments of 0.5 degrees and the best typically go down to 0.1 degrees.
4) Backlighting – in low light or no light conditions,(which is common) this is very helpful for monitoring. Will probably drain batteries at a greater rate, though, plus the glare of the screen may interfere with your night vision.
5) Laser pointer – I have heard some people say this is unnecessary, but I couldn’t disagree more. If you have a thermal anomaly, then you need to pinpoint the area as best you can and the pointer is too convenient to do without. The more sophisticated models have an overlay template which automatically shows the outline of the spot ratio.
6) Display lock with min/max. This can be nice to have, but I don’t consider it essential if you have a halfway decent memory or right things down. There are combination digital with bargraph displays on the more expensive meters which help with picking up on transients.
When using an IR scanner, you need to be mindful that certain materials and angles will create false or erroneous readings.
Some things to keep in mind are
Pointing into the sky will create an artificially low reading
Glass and mirrors will typically false
Be aware of cold air vents, hot pipes and the like which can mislead
Considered to be the ultimate in ghost hunting equipment, I have had the fortune to use several of these devices, including the models below:
Raytheon 400 D 25 mm lens (non-radiometric)
About Thermal Imaging
The Electromagnetic Spectrum
The Infrared region is part of the Electromagnetic Spectrum that is dividing up all types of electromagnetic radiation. This radiation is divided up rather arbitrarily into a number of regions based on their wavelengths:
Gamma < 10 nanometers
Visible light 0.4 to 0.7 micrometers
The Infrared Spectral Range
Infrared is a specific region of the electromagnetic spectrum that is just beyond the light region. The Infrared region spans from 1 to 1000 microns.
Infrared Thermography 3 to 5 & 7 to 14 microns
The regions that Infrared Thermography primarily deals with is the Shortwave region from 3 to 5 microns and the Longwave Region from 7 to 14 microns. The cameras that are used in Infrared Thermography simply see the heat that is emitted from the surface of the object that it is viewing. These types of cameras are used for applications like routine Preventive / Predictive maintenance inspections on electro-mechanical equipment. Where the thermal image of the equipment, as well as temperature measurements, can forewarn a pending failure. The cameras that are used in Infrared Thermography do not see through objects or into buildings through the walls. Infrared Thermograph is:
Infrared Photography 0.7 to 0.9 micrometers
Infrared photography involves the production of photographs by means of near-infrared radiation. This radiation that lies in a range roughly between 700 and 900 nanometers can be recorded on specially sensitized photographic emulsions. Infrared radiation actually comprises a much greater part of the electromagnetic spectrum, most of which cannot be recorded directly by photographic means. Elaborate electronic equipment is required to record heat waves as in Infrared Thermography.
Near-infrared radiation has the ability to penetrate aerial haze, which makes it possible for you to photograph distant terrain, a valuable factor in aerial photography. Even more important is the way in which foliage is recorded on infrared-sensitive emulsions. The internal structure of leaves reflect infrared strongly, so that they appear lighter in tone in the photograph than they do when viewed directly. The usefulness of infrared photography lies in the unique tonal differentiation that it produces. Conifers, for example, appear darker than the leaves on deciduous trees; diseased fruit and vegetable crops or those suffering climatic or nutritional stress can be detected before trouble becomes apparent visually. These features of infrared photography become especially valuable in pictures taken from the air.
Night Vision / Light Intensifiers 0.45 to 0.95 micrometers
In Night Vision systems Gen I/II, in low light situations, the foremost lens collects low levels of light that are reflected off of objects that cannot be seen with the human eye and focuses it on a image intensifier tube. Inside the image intensifier tube a photo cathode absorbs this low level of light energy and converts it into electrons. These electrons are then passed through a microchannel plate that multiplies them thousands of times and drawn toward a phosphor screen. When this highly intensified electron image strikes the phosphor screen, it causes the screen to emit a amplifies image that can be seen with the human eye. Since the phosphor screen displays the image in exactly the same pattern and degrees of intensity as the light that is collected by the objective lens, the bright nighttime image you see in the eyepiece corresponds precisely to the outside scene you are viewing.
This type of systems work great for seeing night time scenes in low light conditions but do not provide a thermal image that corresponds to the amount of heat (thermal radiation) that is emitted from the object. Because of this this type of equipment is not used in Infrared Thermography.
Infrared Viewing Training Tips: Top 10 Techniques
Consider whether the thermogram is going to use to "illustrate" a condition or used to "Measure" a condition. This will greatly effect the type of thermogram that you are going to store. For example you may need to get temperature measurements from a thermogram but you may need to illustrate the condition to others, and the thermogram that you would use to get temperature measurements with most likely would not be the best to adequately illustrate the condition. Understand what the end objective of storing a thermogram is will greatly effect the way you work.
As a general rule, the closer you get to your target, the better your thermograms and temperature measurements will be. Getting close helps to shows the target clearly by maximizing the cameras detectors IFOV across the target providing better resolution.
Think about showing just enough of the scene to make the thermogram clear and provide enough information so that someone can understand what the target is in the FOV. Be sure to check your camera manual to learn the closest distance at which your camera takes sharp thermograms.
If you are working with a infrared camera that can measure temperature then you must learn what the working distance is for accurate temperature measurements of different size targets. This is a key point in being able to accurately measure a object and is the most overlooked parameter in taking good thermograms for temperature measurement.
When working outdoors doing utility inspections most of the equipment is close to ambient temperatures, but the sky is very cold. By silhouetting the target against the sky you focuses attention on the target that will increases the contrast between the background and the target in your thermograms. you may need to move a little to avoid obstructions in the background but the results will be worth it in your thermograms.
There is nothing wrong with placing the target in the center of your viewfinder. However, placing the target off-center can make the composition more dynamic and interesting to the eye.
When taking thermograms of large areas, try including objects in the foreground. Elements in the foreground add a sense of distance, depth and dimension.
When working out side consider what the effects of solar reflection and solar gain will do to your thermograms and temperature measurements. It may be necessary with older types of infrared cameras to work at night to eliminate the solar reflections that show up as faults hot spots.
Sometimes good thermograms are missed by overlooking the basics. Holding the camera steady is vital for sharp, clear pictures. Many older infrared cameras have very slow frame rates so it is very important to hold the camera still when storing a thermogram. When you push the store button, press it gently rather than jabbing it. Even slight camera movement can rob your pictures of sharpness. Use a brace to steady your arm or use a tripod, if necessary.
You can improve the thermogram in many ways after you store the image but you will never be able to get in focus if it was stored out of focus in the field. Take your time to get it right the first time and you will save yourself a trip back to the field.
You must understand what temperatures that you are going to be imaging so that you can set up your camera to view the right temperature range correctly. This will effect not only the quality of your thermogram but also your temperature measurement accuracy as well.
Information posted courtesy of Mayfield Thermography at www.mayfieldinfrared.com located here in Dallas, TX.
"As with sounds, so with colors. At each end of the solar spectrum the chemist can detect the presence of what are known as 'actinic' rays. They represent colors — integral colors in the composition of light — which we are unable to discern. The human eye is an imperfect instrument; its range is but a few octaves of the real 'chromatic scale.'
I am not mad; there are colors that we cannot see.
"And, God help me! The Damned Thing is of such a color!"
from “The Damned Thing”
By Ambrose Bierce