Centrifugally operated wiper mechanism for cleaning turret mounted lenses

A wiper mechanism comprising a wiper, a plate which is rotatably mounted on an axis which is perpendicular to the surface of the plate, means for causing said plate to be rotated, a spring loaded lever on which said wiper is mounted, said spring loaded lever being pivotally mounted on said plate on an axis substantially parallel to the axis of rotation of said plate, said lever being biased into a predetermined parked position by said spring, and a centrifugally operated weight mounted on said lever, whereby when said plate is rotated said wiper is caused to be rotated and, under the action of said centrifugally operated weight is caused to be moved transversely relative to the axis of rotation of said plate form the parked position where it is clear of a surface to be cleaned, to an operating position, in which it is radially disposed relative to the axis of rotation of said plate, in which operating position said wiper contacts said surface.