A psychophysics study, and a tool built on it
A tinted lens cannot add light. It can only remove light differently from the clay and from what is behind it, and whether that helps depends on the clay's pigment, the background, where the sun is, and how sensitive your eyes are to the brightness and colour differences that result. All four are computable or measurable. This site does both.
A first result about three minutes after calibration, the full study in about 25, on a laptop with a keyboard and a plastic card the size of a driving licence. It measures your sensitivity to luminance, red–green and blue–yellow contrast, then tests whether a model can predict which lens classes work for you. You get your profile at the end.
Needs a Clay & Cortex account: an email and a password, the same account as the other studies.
On a phone or tablet? The study needs a laptop or desktop with a keyboard and a plastic card; the recommender below works anywhere. Send yourself the link and come back on one.
Describe the scene (clay colour, background, sun position or the place and time you shoot) and get the predicted clay–background contrast through each lens class, ranked, with the assumptions shown and an honest "no tint helps here" when that is the answer.
Predictions from a physical model. Not yet validated in the field; see the method page.
Part of Clay & Cortex. Built on the same calibration and adaptive-threshold instrument as the trap occlusion study.