Perspective – Tools
The perspectograph is a device or an instrument used to verify or have an aid in the plane representation of the three-dimensional physical space.
The simplest and most used devices are based on the principle already defined by Leon Battista Alberti (1435) of intercepting and blocking the figure with a plane of intersection of the visual cone. These devices can be traced back to two large groups:
- The first group envisages that this plane consists of a sufficiently transparent surface on which the observed image can be directly outlined by placing the eye on a target that forces the operator to keep the point of view fixed.
- In the second group, the intersection plane consists of a grid that divides and organizes the scene in such a way as to allow the artist (always compelled by a target line to maintain a fixed position) to adapt it on an equally squared sheet of paper.
French: Perspectographe – Italian: Prospettografo– Spanish: Perspectògrafo– German: Perspektograph.
The problem of the correct representation of a form in space had a fundamental importance in the history of Western figurative art, especially between the Fifteenth and Eighteenth Centuries. Since the Fifteenth Century, painters have added to the study of perspective the use of various instruments to verify and have a valid aid in the two-dimensional representation of the three-dimensionality of physical space. These perspectographs were also widely used by great artists. The simplest and most used devices are based on the principle defined by Leon Battista Alberti and subsequently codified by Leonardo, of intercepting and anchoring the figure with a plane of intersection of the visual cone; this plane consists of a veil or a glass, in any case a sufficiently transparent surface on which the observed image can be directly retraced by placing the eye on a cannon or a target that forces the operator to keep the point of view unaltered.
Another group envisages an intersection plane consisting of a grid that divides and organizes the scene in such a way as to allow the artist to reproduce it on an equally squared sheet of paper. Albrecht Durer, in a famous etching, shows one of these devices that was used to solve a particularly difficult problem of the foreshortened figure. The device consists of a stretcher that had movable threads, along which are threaded movable beads. When an additional thread is pulled from the object-point as far as the center of the projection a bead is placed to mark where the thread meets the plane of the stretcher. If the side-door, bearing a sheet of paper is closed, then the point marked by the bead can be permanently traced and, point after point, the image will be rebuilt with the utmost precision.
