Taking Panoramic Landscapes - The Easy Solution
I love panoramas. There's something very appealing about their
shape. It's probably because we see the world more in these
dimensions than the near square format of standard film/sensor
frames. It might also explain the upsurge in the popularity of
widescreen TVs!
Panoramas have a reputation of being hard to take. There are
dedicated panorama cameras available but unless you've got at
least a thousand dollars to spare, you probably can't afford
one! But you can take panoramas with any kind of camera.
All a panorama is, is a sequence of images where you turn
slightly for each different frame. In the old days, before PCs
and the likes of Photoshop were around, you'd take your prints
(there wasn't much point in shooting panoramas on slide film,
for obvious reasons), lay them out on a table and position them
over each other where they overlapped. A bit of sticky tape held
them together. [As a side note, this technique was used by NASA
to build up mosaic pictures of the planets and satellites their
spaceprobes visited, up till the late '70s/early 80s when
computers were introduced to make the process less
laborious].
Now that PCs and image manipulation packages are easy to come
by, high-quality panoramas can now be created by anyone. If
you're shooting slide or negative film, you will need to have
your images scanned before you do anything else.
DIY Panoramas
The idea behind taking panoramas with SLR cameras is that the
camera is rotated around its nodal point during each successive
exposure. What's the Nodal Point? It's the point inside your
camera where the light rays converge and flip over. It's
different for different focal lengths (on zoom lenses) and for
different prime lenses (fixed focal length lenses like a
standard 50mm lens). It's important to rotate about this point
to eliminate image mismatches due to changes in parallax.
Parallax is the apparent shift of an object against a background
due to a change in observer position.
Just to be clear, the Nodal Point is not the same as the
film/sensor plane. Generally, for most SLR cameras and lenses,
the Nodal Point is located somewhere towards the center of the
lens barrel and lies in front of the image/sensor plane.
The 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