orthoscopic turns on and off the perspective handling. Turning on orthoscopic rendering removes the effects of perspective. To turn on perspective rendering see, the Field of View command.
Turning on orthoscopic rendering improves the rendering speed by a factor of 2x-4x! So, if you have large images, or are rendering a movie that does not need perspective in the images, try turning off perspective by setting the orthoscopic flag to 1.
set orthoscopic, on set orthoscopic, off