Filming with the Bolex H - Text 5
In addition to this multi-focal clear viewfinder, a second eyepiece is located on top of the camera. Using a complete reflection prism located in the axis of the upper lens of the turret, this eyepiece lets the operator focus on its ground glass. This is an element of the concretization, in the sense in which Gilbert Simondon uses the term,[1] of the principle of the three-lens turret, because with this second eyepiece the various optical axes are reused: the medium axis is used for the exposure window and the higher axis sends the image to the focusing viewfinder. Introducing the reflex viewfinder thus made it possible not so much to correct the problems around parallax as to reorganize the framing and focusing operations: thanks to the reflex viewfinder, these two operations can be carried out without the operator changing eyepieces. This simplifies the camera’s operation, but at the cost of the semi-reflecting prism absorbing some of the scene’s light. All reflex models of the camera, moreover, are equipped with this clear viewfinder, making it possible to prepare the focal length and framing comfortably and precisely before taking the shot. The transition from the H models to the reflex models – contemporaneous with another transformation, the gradual replacement of the turret of lenses with a single zoom lens – is thus a part of a technical evolution which was, in the end, quite complex.
