From Latin 'exponere' (to put out) — literally setting forth for view, from physical revelation to journalistic investigation.
To make visible or accessible; to reveal something concealed; to leave unprotected or subject to risk; to make known publicly, especially something discreditable.
From Old French exposer (to set forth, to explain, to display), a Romance remodelling of Latin exponere (to set forth, to put out, to exhibit, to explain, to abandon), from ex- (out) + ponere (to put, to place, to set down), from PIE *tek- or *apo- + sinere (to place, to let). To expose is literally to put out — to place something where it can be seen. The sense of abandoning infants (Latin exponere) extended to revealing hidden things, and the modern sense of uncovering wrongdoing is attested from the 18th century. The noun expose (a revelatory report) was borrowed back
In photography, 'exposure' preserves the literal Latin sense of 'putting out' — film or a sensor is 'put out' to light. Overexposure and underexposure are technical failures of placing the medium in light for too long or too briefly, making photography one of the few fields where this word retains its physical meaning.