eye-point
/ˈʌɪpɔɪnt/noun
1A point in front of a picture where an observer's eye is assumed or expected to be placed; (also) the point where a perpendicular from an observer's eye meets the plane of a picture. Also in extended use. Now historical.
2The point where the eye should be placed when using an optical instrument or a camera.
Origin
Mid 17th century; earliest use found in Edward Norgate (1581–1650), miniature painter, musician, and writer on art. From eye + point.