Amprobe IR-710 - Understanding Distance to Spot Ratio; Ensuring Proper Field of View

6
Distance and Spot Size
As the distance (D) from the target being measured increases, the spot size (S) of the area
measured by the instrument becomes larger. The spot size indicates 90% encircled energy.
Field of view
Make sure that the target is larger than the spot size. The smaller the target, the
closer you should be to it.