par·al·lax
/ˈperəˌlaks/
noun
1. The effect whereby the position or direction of an object appears to differ when viewed from different positions, e.g. through the viewfinder and the lens of a camera.
"what you see in the viewfinder won't be quite what you get in the photograph because of parallax error"
2. The angular amount of parallax in a particular case, especially that of a star viewed from different points in the earth's orbit.
plural noun: parallaxes