Monitoring movement in difficult to access locations

Cracks often occur in locations that are not readily accessible, for example over a river, railway or road, or high on the outside wall of a building. Because Moiré Tell Tales indicate movement by means of a bold pattern, they can be photographed from considerable distances. A long telephoto lens will allow reading from some tens of metres. Even greater distances can be achieved by attaching a camera to a telescope using a digiscoping adaptor. 

The following image was taken using a digiscoping system. The camera was mounted on a tripod approximately 200m from the tell tale.

The following image is from the same camera and telescope, but with the camera zoomed out. Setting the camera to wide angle when mounted on a telescope causes vignetting, but the image can still be used to record the placement of the Moiré Tell Tales.