Variable perspective viewing device

Claim 1

A variable perspective viewing device for varying the field of the user wherein the device comprises: a first framework unit including a first plate member provided with an enlarged opening having at least two vertically offset and opposed right angles defined by the opening; and, at least one track element; and, a second framework unit including a second plate member provided with a pair of oppositely faced notches defining right angled recesses; wherein, each of the junctures of the notches is aligned with one of the junctures of the said at least two right angles formed in the enlarged opening of the first plate member; and, at least one track engaging surface on the second plate member adapted to operatively engage said the at least one track element of the first framework unit; wherein, the first and second framework units may be moved relative to one another such that: one of said right angled notches cooperates with one side of the enlarged opening in the first plate member to define a variable dimension rectangular aperture; and, the other of said right angled notches cooperates with the other side of the enlarged opening in the first plate member to define a variable dimension square aperture.