Determining lens nodal point.

[chuck]

I am interested in using a panning head to take and stitch together panoramic photos. To get a panoramic photo where both foreground

and background can stitch perfect together seem to require the lens be mounts in such a way that the panning axis passes through the

nodal point of the lens.

 

So my question is, how does one determine where the nodal point of a lens is?

[Rob F.]

<p>It would probably help to say which lens you are using. Someone might already know for that particular lens.</p>

[chuck]

Let's say the 24-70 AFS. Would the nodal point change at different focal lengths for the same lens?

 

But I am interested in knowing how to determine where the nodal point is, or at least where to look it up. You know, give

a man a fish vs teaching a man to fish.

[SCL]

<p>I am assuming you are using a head designed for pano shots, where you can adjust the nodal point to the center of rotation, not just a typical "pan head". The method I use to determine the rear nodal point for a lens is to mount the camera on a tripod with the lens approximately level with and pointing toward a table top. I then place two pencils standing upright ahead of the camera, equidistant from the lens and at an equal angle from the centerline of rotation on the tripod. A second set of upright pens is placed further away from the camera behind the each of the first two along an imaginary line intersecting the point of rotation on the tripod axis. Without moving the tripod, only the bar of the panhead which moves the camera forward and back....look thru the viewfinder. When each set of forward pens on the left side and right side intersect with the rear set of pens, you have established the nodal point for that lens. You can validate that by now rotating the camera about the nodal point, and the pens will stay intersected in the viewfinder. I know this procedure is documented somewhere on the web, but I don't have the URL. It is a very simple and quick process...takes less time than it does to read this paragraph, and it works well for almost any focal length lens. You can do it with a rangefinder camera as well, as long as you can place a ground glass in the film plane for the adjustment.</p>

[Matt Laur]

<p>Yes, it would likely change at different focal lengths.<br /><br />I've been able to quite satisfactorily adjust my spherical pan/tilt head (a Manfrotto device) by tweaking the camera position until I observe near/far object parallax disappear during pans/tilts. Only takes a few minutes once you get the hang of it. <br /><br />There are some good tips here, for example:<br /><br />http://www.johnhpanos.com/epcalib.htm</p>

[Rick Waller]

<p>this makes it pretty clear</p>

<p>http://www.reallyrightstuff.com/Be-a-Gear-Expert/Panoramas-Made-Simple_2/How-to-Find-the-No-Parallax-Point.html</p>

[Ed_Ingold]

I've shot more panoramas with a Nikon 28-70/2.8 than any other lens. The nodal point doesn't change enough to bother

throughout the range. It "grows" very little in length when zoomed.

 

 

If the lens rotates about the nodal point, nearby objects don't shift relative to far objects. "Near" for this purpose varies,

but 75-100 feet is a reasonable number. Caveat - the nodal point varies in some lenses when turned off axis. It's a curved

plane, not a singularity.

 

 

I use a long RRS plate with a clamp on one end. The range is about 7", which has been enough for any of my lenses,

including Hasselblad. The 28-70 uses about half the length.

[chuck]

<p>@ Stephen: I am planning to use a Neewer nodal slide on a Sunwayfoto ball head with a panning clamp. It appear to offer 140mm (5.5 inches) range of movement for the camera.</p>