Distance to Spot Ratio (Field of View)
The meter’s field of view is 12:1 (distance to spot ratio). For example, if
the meter is 24 inches from the target (spot), the diameter of the target
must be at least 2 inches. Other distances are shown below in the field of
view diagram.
Note that measurements should normally be made < 2 feet from the
target. The meter can measure from further distances but the
measurement may be affected by external sources of light. In addition,
the spot size may be so large that it encompasses surface areas not
intended to be measured.
It is necessary to ensure that the size of the target is larger than the spot
size. The smaller the target, the closer the distance should be. See the
accompanying diagram.
