Parallax Error in Meter Reading

Parallax Error in Meter Reading

Parallax is an apparent change in the position of an object when the person looking at the object changes position or line of sight. In meter reading, this error occurs when your line of sight is not perpendicular to the plane of the meter dial.

If you are looking at the meter dial from a distant angle, then you will see a reflection of a part of the needle in the mirror strip. This usually indicates that your line of sight is not correct and the observed reading will have a parallax error.


How to read a meter correctly.

A meter usually has a mirrored strip along the scale to help reduce parallax errors and it does not take long to become accustomed to using it. As you move your head to look directly at the needle, looking head on, then the two needles converge and you see only one needle. This is when the parallax error is at minimum.

Over time, engineers move their heads instinctually to ensure that they are making an accurate observation.