The above drawing represents the mark of the centre of reference as projected on a plane substantially tangential to the lens about the centre of the circle. The lines constituting this mark may either be solid or dotted. | a0c0 |
The above drawing represents the mark of the centre of reference as projected on a plane substantially tangential to the lens about the centre of the circle. The lines constituting this mark may either be solid or dotted. | a0c0 |