Improve your panorama with a nodal slide

Thursday 4 March 2021, 20:40 by Nando Harmsen | 7,805 views | 8 comments

This article was translated from Dutch with the help of AI. Read the original.

Do you make a panorama now and then? Then you know that, when merging the photos, they do not always line up properly.

The problem occurs with elements in the photo that are close by. These errors when merging are caused by parallax.

There is a very simple solution for this: a nodal slide.

Equipment for making panoramas. You can see the nodal slide at the bottom.
With a panorama, you can create very impressive photos. You can capture even more in the frame than you can with an ultra-wide-angle lens. In principle, there is no limit. If you want, you can capture a complete circle: 360 degrees all the way round.

Sometimes the view is so wide that you want, or need, to make a panorama because the widest wide-angle lens is not wide enough. This image is almost 270 degrees wide, three-quarters of the way round.
The best result is achieved with a tripod and a rotating tripod head. Set your camera perfectly level, and take photos with around 30 per cent overlap. That is enough to stitch the photos together seamlessly. Stitching is the English word for this.

When everything in your photo is far enough away from you, this works perfectly. You can capture everything from left to right, or the other way round, and stitch it together.

Software can do this for you very quickly and easily. But when elements in a photo are very close by, the photos do not line up as well.

[cenger]When you have lots of elements in the foreground, the parallax problem can occur. The photos do not line up exactly. This photo was taken 360 degrees all the way round.

The parallax problem

It almost sounds like the title of a Dan Brown novel: the parallax problem. Nothing could be further from the truth. Parallax is what occurs when we look at something from slightly different viewpoints.

We do nothing else with our eyes, and it is precisely these parallax differences that allow us to see in three dimensions.

Put your camera on a table and look at it. Close your left eye and pay attention to what you can see behind the camera. Then close your other eye, making sure you open your left eye again, and see what happens. Your camera has a slightly different position relative to the background. That is parallax.

Now put your camera on a tripod, position it perfectly level, and make sure you have a nearby subject in the frame against a background that is a little further away.

Turn on live view, and watch how the position of the subject changes relative to the background as you rotate the camera. That is parallax.

Parallax means that your elements do not line up in the same way when you rotate the camera.

Parallax errors

The shifting of a foreground element relative to the background becomes a problem when you want to stitch your photos together. Sometimes the software can correct this to some extent, but usually that is difficult or even impossible. Then you have stitching errors. In Dutch, these are called parallax errors.

To do this seamlessly, the foreground must remain in exactly the same place relative to the background. In other words, the background must not shift when you rotate the camera. To achieve this, you need to place the rotation point in exactly the right position. This is called the nodal point.

The nodal point is somewhere inside the lens. This is the point around which you need to rotate.

Rotating around the nodal point

When you put the camera on a tripod, the camera rotates around the position of the sensor. Instead, you need to rotate the camera around the nodal point. This is a point somewhere inside your lens. Once you have found this point, parallax errors are avoided.

You therefore need a tool to position your rotation point underneath your lens. This tool is called a nodal slide. Do you want to make perfect panoramas? Then a nodal slide is essential.

With a nodal slide, you rotate around the nodal point and prevent parallax.

Where can you find the nodal point?

Where the nodal point is located depends on your lens and your focal length. You will have to work this out by trial and error. You do need a nodal slide for this, of course.

For this, place two subjects in line with each other, just as I did in my example photos. Then rotate the camera and move the camera forwards or backwards until the two subjects remain perfectly behind each other regardless of the rotation.

Rotating around the nodal point prevents parallax. Compare this with the earlier triptych, which was rotated without a nodal slide.
Most nodal slides have a scale. Note down where the nodal point is for your lens and focal length. This allows you to set everything up perfectly straight away on location and prevents the photos from failing to line up exactly because of parallax errors.

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