Photographic test and calibration charts are used to confirm that colors match the scene in which they’re captured, ensuring that the camera and lenses are performing to their maximum ability.
Many charts have expiration dates stamped into them, and it has become general practice to replace them every few years.
Through collecting and documenting so-called “retired” and obsolete charts, I wonder about how notions of photographic accuracy have changed throughout the development of the medium. Is “red” from a 1950’s photographic card still as “red” as a 1980’s TV test chart? Can a contemporary lens still resolve to the maximum power illustrated in a test chart from the 1960’s?