Taking Panoramic Landscapes - The Easy Solutionby Gary Nugent
he Problem With Parallax
Parallax is easily demonstrated by a simple experiment. Hold up your finger about 1 foot in front of your face and alternately open and close your left and right eyes. You'll notice that your finger shifts left and right with respect to the background depending on which eye is open. Try another experiment: With your finger still raised, close one eye and turn your head from side to side.
Notice how your finger moves with respect to the background. This relative movement is due to the fact that you’re not rotating your head around your eye’s nodal point, which is somewhere in the center of your eyeball. Instead, you’re rotating about your spine which is several inches to the rear and off to one side. It is this relative side-to-side motion that we try to eliminate when setting up a camera for panoramas. [If you want to read up more about parallax, Wikipedia have a good explanatory article.]
Now, if you consider a camera held up to your face - it will suffer even greater parallax errors as it's farther from your spine (the point of rotation of your head) than your eye. It's surprisingly common for people to take panoramas in this fashion and then find the individual pictures don't match up.
So use a tripod and rotate the camera on the tripod. The parallax errors will be significantly smaller but there will still be some error involved. However, the images will match up better than with the head rotation method.
What perfectionists strive for is to have the camera rotate about the nodal point. There are brackets and contraptions available that will let you offset your camera from the tripod's axis of rotation and with a little experimentation and trial and error, you can position your camera so that its nodal point is directly over the axis of rotation of the bracket. Getting this spot-on means your images should line up perfectly.
A few months ago I bought such a bracket - the Kaidan Kiwi. This comes in two halves which produce an L-shaped bracket. Its instruction manual explains how to set it up and find the nodal point for your camera and lens. However, you have to get your tripod perfectly level before using it, otherwise you end up with a curved panorama rather than a straight one.
I've had good success using this bracket, but it is large and heavy and certainly a bit too cumbersome to be carrying on long walks or while away on vacation.Page 2 of 3. (To continue this article, go to AutoStitch To The Rescue)