To split a hair: you can focus by moving the rear standard too.
Originally Posted by ReallyBigCameras
Usually with this design, it's said that you set the rear standard appropriately for the focal length in use, and then you focus with the lead screw. But those are just two different ways of accomplishing the same thing: positioning the lens relative to the film to bring the image into focus.
Of course, "rear focus" in this case isn't geared, and it's not ideal for fine adjustment. But for those setups where focusing by moving the front standard is problematic - for example, because of changes in magnification - the Chamonix at least allows you to easily do coarse focus with the rear standard, so that the remaining fine focus that's required moves the front standard only minimally.