Best targets to calibrate camera with long focusing distance

1. What distance should I calibrate my lens?
2. How many points are needed for camera calibration?
3. Why are many images needed to calibrate a camera well?

What distance should I calibrate my lens?

To calibrate your lenses, set your camera up on a tripod, or flat surface like a table, and set the focus pyramid on a level surface about 6 feet away. I usually set it up at a distance that I typically shoot from, that way I know it's accurate at the distance I shoot at the most.

How many points are needed for camera calibration?

The traditional way to calibrate the camera is to take images of a known calibration grid. Six points are needed to obtain 12 equations.

Why are many images needed to calibrate a camera well?

All cameras see colors differently and to recreate a scene as you remember it, you might have to make a number of edits in post-processing to render the colors accurately. Calibration will mean you have a better, more accurate starting point and so each image will, in theory need fewer edits.