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Shooting Guide for Lens Calibration Grids

If you're going to be shooting lens grids for a project (ie for all anamorphic projects), here are some tips to make it worth the time.

- Always use a perfectly regular array of dots or checkerboard. See our online grid generator.

- Don't have inset "higher resolution" sections: keep the pattern the same.

- Use many dots or checkers to maximize accuracy, especially on high-resolution cameras and with anamorphic lenses. Only the dot center or corner locations provide useful information, not white space or edges.

- Always print grids on a large-format printer. Never paste/tape/glue pages together.

- Measure width and height and length of both diagonals of the printed grid to check the aspect ratio and watch for any skew in printing.

- Make sure the grid is flat. Rigid canvas frames may be flat truly planar. Foam-core and cardboard are not flat. Walls and glass doors aren't necessarily flat. Consider printing on metal with vendors such as WhiteWall?

- Always have grid extend to the edge of the image! (Fisheyes lenses too!) All the useful information is towards the edge of the image. Pixels past the edge of the grid will often be unusable in production shots.

- Keep the camera axis perpendicular to the plane of the grid as much as possible. You can assess this by comparing the left and right edges of the image, and the top and bottom edges of the image.

- Provide even lighting over the grid.

- Use the same lens settings (focus distance, iris, and zoom) as the live shoot as much as possible. Shoot some different combinations if there are large changes.

- Focus! Defocused grids will degrade accuracy and may prevent automated tools from detecting the dots or corners, requiring manual fixups.

- Use the same camera settings as the live shoot: HD vs 4K, photo vs movie, etc.

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