This section describes how to copy paintings or prints using the camera obscura. It explains the positioning and adjustments needed for the board and convex glass to achieve accurate or altered sizes of engravings. The process involves manipulating the distance and orientation of the board and engravings in relation to the sun and the device.
Chapter VI
Method for Copying Paintings or Prints with the Camera Obscura.
25. The paintings and soft engravings you want to imitate are attached to board F (figure 1) on the side facing the back of the machine, which should be turned so the engravings are exposed to the sun. In this setup, they are shown (14) like other objects, with the sole difference being that the convex glass in cylinder C must be changed. If the aim is to give the print its true size, the distance from the focus to the glass should be equal to half the height of the machine above the table, i.e., half of AC. If one wants to give these same figures more size in drawing than they truly have, the focal distance should be even shorter; conversely, it should be longer if one wishes to represent figures smaller than they are. The required adjustment of the engravings' distance is achieved by moving the board F forward or backward until they appear clearly in the device. Note that when figures are to be moved beyond the back of the device, they must be fastened against side F of the board and turned by passing its bars through the guides DE, DE, so that face F looks toward opening N.