Methods of manufacturing security documents and security devices, and corresponding products, provide a lenticular device effect in a first registration zone. Viewing its appearance from two different angles in this way, the relative positioning of the focussing element array and the image array can be judged to a high degree of accuracy. If the two arrays do not have the desired relative position, this will be clearly apparent since the different first and second images will not be captured at the first and second test viewing angles.