Most if not all of the photographic heads used for shooting spherical panoramas are fitted with an horizontal arm on which a vertical arm is fixed.
A third arm is mounted via a rotator on top of the vertical arm and can revolve around the horizontal axis of the rotator: the camera is mounted on this arm and can shoot images at different inclination angle, in several rows of images to be stitched later in a single panoramic image.
An illustration shows this principle in a nice animation on the Nodal Ninja home page.
The root of vertical arm has to be located precisely along the horizontal rail of the lower horizontal arm at a place that depends solely on the Camera: the distance from the axis of the camera lens mount to the camera mounting base plate varies from one camera model to an other...
The (NN5) panohead that is presented on the Nodal Ninja's animation is a precise mechanical assembly as are of course other top-of-the-range products made by Fanotec's competitors. Some accesories help in mounting the camera in a precise, adequate and repeatable position such as the (anti-twist) Camera Mounting Plate CP-2.
Benefiting from the mechanical features precision of the NN5, we shall accurately adjust the vertical arm position along the lower horizontal arm by using a method that doesn't require to shoot a photograph. As a matter of fact, the camera can even be switched-off!
The key elements are
We could make the experiment when the head is dismounted from the rotator( please read this older article), but moreover we shall demonstrate here how to do "on the tripod while on the field" e.g. when exchanging your camera with a new one that you borrowed from a colleague panographer.
NOTE: The camera is mounted on the Upper Horizontal Arm but in the reverse direction: unlike the correct fashion, when the arm is pointed downward, the camera is then pointed toward the Nadir!
Move the vertical rail along the horizontal rail until the red pin head can snap into the hex hole of the hex crew head when the camera is gently pushed down along the Upper rail. Then, screw the knob to fix the Vertical rail. The camera can be put back in the right direction. That's it.
You may watch these movies and check that the pin head snaps into the hex screw hole...;
2 March 2010