Tuesday, May 29, 2007
The Really Wide View
Panoramas are hot with a lot of clients right now, but shooting them well takes specialized skill and attention to detail
Getting The Alignment Right
To get the best results, mount the camera on the panorama apparatus with the nodal point set right over the rotational axis and shoot away. Ah, if only life was that simple. Lens manufacturers don't mark the nodal point of the lens on the barrel, and the nodal point on a zoom lens changes as the lens is zoomed. Therefore, your first task is to align the nodal point properly.
First, get the whole setup as level as possible. If you're not level, you'll end up with distortion, and you'll have to crop to make the final image. Bubble levels are good tools for leveling everything up. When you're leveling, do so with the tripod first, then mount the camera. Panorama mounting setups will allow you to make fine adjustments to get everything square—that's just one of the reasons why they're so essential for this kind of photography.
The next step is to get the lens centered over the rotational point. You can almost eyeball this, but it's better to use a plumb line to get it as close as possible. Try taping the line on top of the lens, and you'll be able to line up the lens center and the axis of rotation quite easily.
Once you're leveled and mounted up, finding the nodal point is a visual process. Looking through the viewfinder, find a vertical line in the foreground and another one in the background. Slide the camera fore and aft on the bracket as you rotate the camera, and watch the alignment of the vertical lines. When their relationship doesn't change (no parallax), you're aligned on the nodal point. If possible, you want a good straight vertical line that's close to the lens and one that's near infinity. For the near line, you can use a spare light stand if you have one handy. As you're rotating, if the foreground edge moves in the same direction as the pan, you're mounted too far behind the nodal point—slide the camera forward; if the foreground edge moves in the opposite direction as the pan, you're mounted too far in front of the nodal point—slide the camera aft. Of course, you can set up a scene and find and mark the nodal points of all your lenses in one fell swoop; then when you're setting up a panorama, the mounting process will be much faster. If you're planning on doing a lot of panorama shooting, going through the process of finding the nodal points of all your lenses makes a lot of sense.
There are plenty of times when you won't have those vertical edges. In those instances, go through the same steps, but as you're rotating to get nodal alignment, try to watch for changing perspective relationships. The closer you get, the better, but if you're not dead-on, it won't be the end of the world.
Chances are good you'll find one or two lenses that you use for all of your panorama shooting. With a little practice, getting everything mounted and properly aligned will be fast and easy, and you can get right down to shooting.
You'll be shooting vertically and stitching together a number of frames. Be sure to lock your camera's exposure and focus so nothing shifts from frame to frame. If your exposure settings move during the process, you'll end up with frames that simply can't be integrated together. Give yourself plenty of overlap to overcome any lens distortion and to make the actual stitching easier. Most pros who do a lot of panorama shooting stitch the frames together manually in Photoshop, but if you're determined to use a more automated approach, try PTGui (www.ptgui.com) for Windows or Realviz (www.real viz.com) for Mac and Windows. These packages enjoy excellent reputations and can make the job much faster.
There's no question that panoramas make a visual impact. Adding some of these unique compositions to your portfolio demonstrates your versatility when you're pitching clients, and that just might lead to a good gig down the road. There are relatively few professionals making high-quality panoramas. Learn to do it right, and you can jump to the top of the pyramid.
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