Also parallax shift. Apparent shifts of an object when viewed from different positions.
The classic example involves holding a finger in front of your face, slightly off-centre, and looking at it first from the left eye and then the right. The finger appears to shift, since the finger-eye distance and angles are different for each eye.
Binocular disparity caused by parallax is one of the most important ingredients in human visual depth perception. Parallax shift is also exploited by 3D viewing systems, such as anaglyphs. Parallax error, on the other hand, is a problem when shooting VR images.
Parallax error is also a problem when youre using any camera system in which the viewfinder is a separate optical system from the actual taking lens. In an SLR, parallax is not a problem because when you look through the viewfinder youre looking through the same lens which takes the photo. But with a TLR camera the viewfinder and taking lenses are separate. Closeup photography is thus a real problem with TLRs, because you have to compensate manually for parallax shift. However, parallax becomes less and less of a problem as the subject to camera distance increases. (this is why the moon seems to stand still when youre driving along a road at night)
cf. single lens reflex (SLR), rangefinder, taking lens, twin-lens reflex (TLR).
Entry last updated 2002-04-03. Term 883 of 1487.
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