Bolex Product Code :- RACKE
The Bolex Rackover Unit has only any real value when you want to shoot a close up of something less than 20 inches from the lens and you only have a Non Reflex camera but one that has the Critical Focusing Screen built into it.
If you have a Non Reflex camera without the critical focusing screen then you will have to use the Critical Gate Focuser. If you have a reflex camera then you do not need this device at all!
The Rackover Unit attaches easily to the camera's tripod mounting thread by using a screw. Once the camera and Rackover Unit are attached together the Rackover Unit can be screwed onto a tripod.
An operator can now move the lens he/she wants to use to shoot a scene in front of the critical focusing screen in order to frame correctly the subject to be shot. After the subject has been framed correctly the lens can be moved in front of the film gate to actually shoot the scene.
The Rackover Unit compensates for the parallax error involved in focusing a subject in one position and then taking the shot in another. Because the error always stays exactly the same in a Bolex camera with a critical focusing screen the distance between the focusing screen lens position and the film gate lens position is always exactly the same, so a device could be devised to get rid of it.
You focus the camera with the lens you want to shoot the scene with in front of the critical focusing screen with the camera at the bottom of the rail of the Rackover device. When you have framed the scene you can move the lens down in front of the film gate and move the camera up the ramp to compensate for moving the lens.
The Rack over device moves the entire camera vertically and Horizontally at the same time to compensate for the parallax error that occurs due to the critical focusing screen being higher and to the left of the actual taking lens. It is also necessary to make sure that the camera is completely level before taking a shot.