Traditional Culture Encyclopedia - Photography major - What is parallax?

What is parallax?

Parallax is the direction difference caused by observing the same object from two points at a certain distance. Seen from the target, the included angle between two points is called parallax of two points, and the distance between two points is called baseline. As long as the parallax angle and baseline length are known, the distance between the target and the observer can be calculated. Conceptual editing paragraph

In physics, it refers to the phenomenon that the relative position between near and far objects changes when observed in different positions.

In astronomy, it refers to the change of direction caused by the observer's position moving or observing the same celestial body from different places; Measuring the parallax of celestial bodies is the most basic method to determine the distance between celestial bodies. Astronomers used this method to measure the distance between the moon (analyzed from photos taken in new york and Washington) and Swan X 1 in the early days.

In photogrammetry, it refers to the coordinate difference of image points with the same name on a stereo image pair, and its abscissa difference is called "left and right parallax" and its ordinate difference is called "up and down parallax"; In aerial photogrammetry, the left and right parallax can be used to calculate the height difference between ground points, and the up and down parallax can be used to determine the relative relationship between photos during photography.

In photography, it refers to the phenomenon that the position of the object seen from the camera viewfinder is inconsistent with the position of the object photographed by the lens; The farther the camera is from the object, the smaller the parallax; The advanced viewfinder has the function of correcting parallax, so that the position of the object on the photosensitive imaging and the position seen from the viewfinder are consistent regardless of the distance; SLR cameras basically have no parallax because the viewfinder and photography pass through the same objective lens.

Explanation (1) parallax is a phenomenon that it is difficult to make accurate experimental measurement because of the relative motion between the ruler and the measured object with the shaking of the eyes (the observation position changes slightly) during the adjustment of optical experiments.

⑵ Causes of parallax: Because the measuring ruler (reticle) is not coplanar with the measured object (image), when the eyes shake (the observation position changes slightly), there will be relative movement between the ruler and the measured object.

Parallax means that there is a certain gap between what you see and the objective form of the object.