There are many different ways to find the best point to turn a camera when shooting for stitching panoramas. This point is called NPP (No Parallax Point). Stitching pictures that have parallax errors is usually much more problematic. The commercial panoramic tripod heads allow you to adjust the camera position and make it easier to find the NPP. In other cases the NPP is already defined as in this database. In other cases, as for those who want to build your own DIY panoramic tripod head or use a philopod more accurately it is interesting to know exactly where this point is located.
I show you here a simple way to find the NPP based on simple things. The use of a cell phone at the video was intentional, to show that any equipment has its NPP. Not by chance, the NPP of a phone is over the lens vertical. This point corresponds to the lens entrance pupil, like our eyes pupils. It’s where the light rays converge in a point to then form the image at the camera sensor. This point will usually be in some place into the lens. Usually closer to its front side and in small lens, like in a cell phone, basically on it. In big lenses, like on DSLRs, is where it is more important to find this NPP, where there is a chance of a bigger error.
To make things even simpler, follows a prepared sheet of paper that you can print. Without it you will need a ruler and a pen or pencil.
What you will need:
- A sheet of paper, whether the prepared sheet of paper or a blank one
- A paper clip
- Tape
- An object to put in front of the lens – the closer the better
- A table or any flat surface
- An object or scene as distant as possible – the more far the better
- If your camera don’t stay stand up by itselt, something to do it
As an option you can download the video (259MB).
In short terms:
- Fix the clip on the flat surface and stick the paper so that it turns around the hole of the clip
- Put the camera in a way that the lens centre passes through the radial line that comes from the axis at the clip.
- Put an object close to the camera and another far away
- The closer object mustn’t be over the paper in order not to turn with it
- The more far object don’t need to be put there by you, can be anything from a far scene
- Turn the set paper+cam keeping the axis on the clip
- When turning the relative position of the close and the far objects must remain the same
- You must move the camera on the paper keeping it parallel to the axial line until the objects relative position don’t change when turning
See you, Cartola.