This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
View through optical plummet. control network through the optical plummet of prism adapter on tribrach on surveyers tripod There is obviously big centering error When the tribrach is properly centered above the point the crosshairs will split the inner diameter of the tube in four equal pieces Photo taken in Vaxholm in the Stockholm