Memento

"Say cheese!" -- Henrietta Helmholtz

You hold up a glass sheet and peer through it, etching your view into its body for the duration. The surface will show what you have seen through, immortalizing the moment once you blink. The memento reflects your perception, allowing it to capture any illusions and other anomalies invisible to another set of eyes.

A memento can be made permanent by developing it. this process requires an hour of concentration on the memento in a pitch-dark room. A developed memento loses its image upon its surface being cracked, or if Dispel magic is cast upon it.