How to eliminate parallax.

Even if your setup is perfectly level, you won't be happy with the results until you eliminate image parallax. Image parallax occurs when near and far objects don't align in overlapping images. For example, if you're shooting a scene that contains a fence line, each fencepost in image 1 should line up with its twin in image 2. You can eliminate the effects of parallax by placing the optical center of the lens (not the camera) directly over the point of rotation.



Canon 5D Mark III with 16-35mm/f2.8L lens. Camera fitted with B5D3-LA plate; mounted on MPR-CL II nodal slide and PC-LR panning clamp. Note how the nodal slide has been used to shift the camera back so that the optical center of the lens can sit atop the axis of rotation (in this case, the center of the panning clamp).

SEE IMAGE ABOVE:
• Vertical red line: axis of rotation
• Horizontal red line: lateral centerline of lens axis
• Yellow lines: light rays cross in the optical center of the lens

YOU'RE READY TO SHOOT PANOS WHEN YOUR POINTS OF INTERSECTION CONVERGE

But how can you shift the camera and lens backward when your camera body plate only slides left/right? Add one of our nodal slides. These rails with clamps mount to the bottom of your camera body plate and are the perfect way to shift your camera & lens back so that the No-Parallax Point of the lens can be correctly positioned directly over the pivot center.

LET'S CALL IT WHAT IT IS: THE NO-PARALLAX POINT

There's friendly controversy over the correct term. But for the sake of visual simplicity, we'll stick to the term "No-Parallax Point" or "NPP" when referring to the point about which your setup should rotate.

PARALLAX EQUIPMENT

This concept can be bewildering, but its influence on creating seamless panoramas can be demonstrated with a simple experiment rather than through an optics lesson. Try the following experiment: With one eye closed, extend your arm and point your thumb up. Line your thumb up with the side of a door frame. Now, turn your head left and right. Notice how the door frame shifts as you turn your head? This is an example of image parallax because your eyes are not in the middle of your head. You can also do this experiment with a camera and attached lens (it's easier to start out with a prime lens since the NPP point tends to be close to the physical center of the lens).

Pivot the camera left and right over its tripod mount and you will notice the same effect as background objects shift relative to foreground objects (say, a nearby fence post versus a distant fence post). But if you pivot the camera at a specific point under the lens, you'll notice that the near and far objects remain aligned. This is the No-Parallax Point. The idea is that parallax can be eliminated by mounting the camera on the ball head so the NPP of the lens sits directly over the rotation axis of the ball head.

IMAGE SETTINGS

• Decide how much depth of field you want across the entire scene and choose an appropriate aperture. Since most panoramas are of places and not people, you can set maximum crispness and depth of field out to infinity by focusing on the hyperfocal distance.
• Set the camera's exposure mode to Manual; exposure across the scene needs to be consistent. If you're not comfortable with manual exposure settings, take a few shots in Aperture Priority at your chosen aperture, note the shutter speed, and use that setting for manual exposure.
• Set your White Balance manually.
• Decide how much overlap you need. A rule of thumb is 30-50%, but the actual amount of overlap is not that important and the amount of overlap can vary from image to image.

EXAMPLE: SET YOUR GEAR UP TO FIND YOUR NPP

Mark, a Really Right Stuff Customer Service Rep, is setting up his Nikon D780 to find the NPP of his 16-35mm zoom lens. He aligned two vertical objects inline with his lens; Mark used two TA-3-FS tripod foot spikes mounted upside down, but any similar item works well. To his standard support gear (TVC-33 tripod, BH-55 LR ball head, and L-plate) he added our PG-02. When you're shooting a pano, you don't want the background to shift in relation to the foreground from frame to frame. So that means you need to shoot from the same perspective for all shots. To do this, you must find the lens' center of perspective "the NPP" and rotate your gear about that point. Here's how to do that using our Pano Elements Package.

Article Version: 1.01.09.22