Drawing with a Grid Around 1530 – Albrecht Durer
Next Sunday at Ohavi Zedek we will be drawing from photos using transparent grids, transposing the shapes and values from the photo to a large, similarly proportioned grid, on drawing paper. The medium used can be graphite, ink or charcoal.
Before cameras this process was done from objects in the three dimensional world using a frame placed in front of an object, and a cord or string attached to a stylus placed at any point on the object, running through the frame to a spot behind it to a pulley on a weight. The position of the pulley would be the position of an eye viewing the object through the frame. As the cord passes through the frame, its coordinates with respect to the side and top of the frame are precisely measured, and a corresponding mark is made on the plane at that point by closing a door hinged to the side of the frame. A series of marks made on the plane, corresponding to a series of positions on the object as seen by an eye (at the position of the pulley,) creates a planar projection of the object as it would be seen looking through the frame at the object.
All the mechanical details are obviated by the camera, which places the planar projection on a two dimensional sheet for us. The photo is the equivalent of the plane inside the frame below. Durer has beautifully explained the whole thing graphically. Look carefully so you can see what the gentlemen in the engraving below are doing. Click on the image to get a larger view so you can see the details more clearly. 
