parallax error

The term parallax error is used, among other things, in metrology when measuring with pointer instruments. It is understood as the relative displacement of the pointer to the display scale.

Due to parallax errors, the reading of the measured value is shifted by the distance at which the pointer is located in front of the display scale and depending on the eye with which the measured value is read.

To reduce or avoid parallax errors, pointer instruments are therefore equipped with a mirror scale. The parallax error is eliminated when the pointer and the mirrored pointer are congruently visible above each other.