How wrong can my temperatures be?

I have often been asked this question by students, and it does surprise them when they find out. The accuracy of high quality cameras is +or- 1 degrees or 1%, whichever is the greatest (low quality cameras it can be +or- 5 degrees). This means then under most normal conditions the camera will only ever be off by 1 degreesC, however, the operator can be off by hundreds of degrees, if he has not input all the settings in the camera correctly.

Screen Shot 2012-09-15 at 13.49.00

The image above displays the correct temperature of 74.6 C, using all the correct camera inputs.


Changing just one camera input, changes the displayed temperature to 132.3  C. This would cause a measurement error of 57.7 degrees C, far more than the specified accuracy of the camera system used.