Abstract: In an optical transformation drawing apparatus in which an image is projected by a projector on to a rear face of a projection screen so that a draftsman can trace on the front face of the screen the image transmitted through the screen, both the projection screen and a projector support frame supporting the projector are mounted on a fixed frame to pivot about an axis with the projector support frame and the projector thereon acting as a counterweight for the screen and with the projector support frame arranged parallel to the pivot axis, a mirror being provided to deflect the image from the projector on to the rear face of the screen.