Finding the No-Parallax Point
The simple steps outlined below are sufficient for finding the optical center (aka No-Parallax Point or NPP) for most shooting situations. But some shooting situations are more demanding, and may require a method that delivers a higher degree of precision. For example, No-Parallax Point positioning is absolutely critical anytime you're shooting a scene that has diverging/converging lines (roads, paths, fence lines, windows, etc), especially when these elements are in the foreground and close to the camera. In that case, skip to the bottom of this tutorial for further recommendations. Once you've found the No-Parallax Point for your lens, make a note of it so that you can easily repeat your setup the next time.
Level Your Gear
ONE STEP LEVELING
If you use our panning clamps, this step is a snap. Loosen the ball and shift the clamp until the spirit level indicates it's level, and in one step, you've leveled both the camera (the lateral axis) and the panning base (the axis of rotation).
TWO STEP LEVELING
Alternatively, level your tripod and camera separately. When you level the tripod, what you're really trying to get level is the panning base of your ballhead. For leveling the tripod, a leveling base or a leveling center column makes the first step quick and easy. And to level the camera? Use the spirit level built into one of our clamps, or use a double-bubble level mounted in the camera's hot shoe.
Position the NPP Over the Axis of Rotation
Where is the No-Parallax Point? The physical location of the optical center is unique for each lens. For prime lenses, the No-Parallax Point (with focus at infinity) is stationary. For zoom lenses, however, the No-Parallax Point typically shifts for each focal length. The location of the No-Parallax Point is commonly expressed as its distance, in millimeters, forward of the film plane/digital sensor.
The No-Parallax Point is best determined by experimentation: Use a "nodal slide", such as our 7.4-inch (188mm) long MPR-CL II. The objective is to slide the camera along its lateral axis until the No-Parallax Point is positioned over the axis of rotation. Precise positioning is critical if your subject matter is close, but much less important if you're shooting distant landscape shots.
• Find two vertical objects; one near, one far. Position your equipment so that these objects line up in the viewfinder.
• Level your equipment.
• Mount and center your camera on the MPR-CL II.
• Start out by positioning the approximate center of your lens over the axis of rotation.
• Now pan left.
• If the rear object appears to shift to the left, then you are ahead of the No-Parallax Point. Slide the MPR-CL II forward and try again.
• If the rear object appears to shift to the right, you are behind the No-Parallax Point. Slide the MPR-CL II back and try again.
• When the optical center of the lens is directly over the axis of rotation, the rear object will not appear to move relative to the front object.
• Record your results so that your setup can be re-created.
No Parallax Point List
Known No-Parallax Points for some camera & lens combinations are found here. If you find your combo, simply line up your MPR-CL II nodal slide at the NPP listed below and you're ready to go! This table assumes that...
• You are using a Really Right Stuff camera body plate
• Your camera is mounted in landscape, not portrait
• You are using a Really Right Stuff MPR-CL II nodal slide
Have you already determined the NPP for other camera & lens combinations? Please share them with other Really Right Stuff customers by emailing us your list. For negative value NPP measurements, simply rotate the MPR 180 degrees.
*Note About Your Camera Body Plate
If you are using an Arca-Swiss style mounting plate that was not made by Really Right Stuff, you may have to make an adjustment since the dovetails on your plate may not be in exactly the same place as the RRS plate.
**Note About Landscape Mode
Even though we recommend using a L-plate to shoot panoramas, we've listed the NPP with the camera mounted in landscape. Why? Well, the mounting dovetails on our L-plates are not always aligned with each other. To give proper clearance to the ports on the side of the camera, some L-plates have to be designed with the dovetails offset. When this has to be done, we try to position the offset at exactly 10mm to make the NPP positioning change quick and easy. If the dovetails on your L-plate are aligned, then you don't need to make any adjustments when turning the camera to portrait.
***Note About Your Nodal Slide
Our MPR-CL II nodal slide has a fixed clamp position. But you may be using one of our nodal slide packages with a sliding clamp. In that case, you should fix your sliding clamp at the position indicated below to simulate the MPR-CL II. 192 FAS Package: Fix your FAS clamp with the indicator at 16.7cm. 192 Precision Plus Package: Fix your mini-clamp so that the centering index mark on the bottom clamp is at 16.7cm.