Camera

Although it's possible to buy lenses that will take a 360-degree panorama in one or two shots, this is very expensive and it imposes unpleasant limitations on your panorama. Most people who do this work go the multi-image route, shooting 12 or more images from a tripod, then stitching the images together using one of the powerful software packages now available for this purpose.

This sounds really straightforward, but of course there's a catch. If you just mounted a camera on a tripod and took a series of shots, all the detail close up would be blurred. I'll skip the technicalities (which are described in detail in the tutorials found in the Links section). To overcome the problem, you have to mount the camera so the pivot point around which the camera rotates is not the mounting hole, but the nodal point.

    

Camera, tripod and home-made QTVR mount. While a tripod normally mounts the camera body directly over the centre of rotation, the QTVR mount centres the nodal point, which is approximately in the lens' middle, over the rotation point. This shift eliminates the parallax differences between successive images that would be created by a normal mounting position. Parallax differences create blur in the finished movie.

An image collected by a camera lens is inverted before being recorded on film or the sensor (I'm not sure if this is physics or sheer perversity). The point at which this happens is the nodal point, and at this point, the parallax that causes blur in stitched images is non-existent.

To mount the camera's nodal point over the pivot point, you can either spend $400 or $500 for a special mount, or you can make one. I made one, for a total cost of about $5.00, most of which went for the adhesive measuring tape seen on the left side, which made it easier to run through the trial-&-error process of locating the nodal point.

The mount is an aluminum angle mated to a piece of flat aluminum by two machine screws sliding in a slot, all in turn mounted on an ordinary tripod. Expensive mounts have lots of levels built in; I use a $3.00 level from the hardware store to adjust the leg lengths to ensure that the top of the tripod is level. The same level ensures that the base of the mount is level.

This mount works very well for single-row (or cylindrical) panoramas, but there is a limitation: when the camera is tilted up or down for an upper or lower row of images, as is required for a multi-row (or spherical) panorama, the nodal point no longer is over the pivot point. This hasn't been a problem so far, but Mount Mk. II will address this issue.