Here is another fun but not too scientific way to determine the spot size of your Infrared camera:
1. Cut a one inch round hole in a paper plate.
2. Convince a co-worker that this will not make him look strange.
3. Have your co-worker stand close to you and measure the temperature of his forehead with the camera. You do not have to worry about the emissivity value of the skin, just make note of the temperature the camera is recording.
4. Next, have your co-worker hold the paper plate to his forehead.
5. Take the temperature reading of his forehead.
6. Have your co-worker slowly back away until you see the temperature change.
7. At the point the temperature begins to change, measure the distance from the camera lens to his forehead.
The spot size extends from the camera lens in a cone shape. You have just determined the distance at which the spot size is one inch in size. Let's say you have a 1 inch spot size at 12 feet. Now you can determine how big your spot size will be at 24, 36, or 48 feet. Let's say you are looking at a target 68 feet from the camera. What would the spot size be? It would be 68/12 or 5.67 inches in diameter.
If the temperature in step 5 immediately changes, you may have to go to a larger hole size. Try 2 inches and repeat the procedure.
Tip Provided by: Arby Dickert, America's Sales Manager IRISS, Inc.