It's said that our lives flash before our eyes when we die. But what if the final moment could be captured forever? What if the last thing we see before we expire was bleached onto our retinas, a parting shot as we drift into oblivion?
That's the principle of optography, which the British artist Derek Ogbourne charts through a constellation of convoluted tales, shaky documentary and drawings in The Museum of Optography.
It is the sixth time that Ogbourne has pitched up his nomadic museum and describes this Sharjah version as its fullest iteration yet.
While it's impossible to pin down exactly what The Museum of Optography is (for reasons that become clear as we tour its voluminous halls), it begins with the artist being punched in the face on a London street in 1992.
A ring on the mugger's finger gashed Ogbourne's forehead. He lost a lot of blood and the event left him with a fear of crossing the street because a bus nearly hit him in the scuffle.
But as Ogbourne recouped, he came across a paragraph in a Time-Life book outlining the theory behind optography.
The Museum opens with a selection of paraphernalia leading up to that point - the bloodstained white trousers he was wearing the night he was punched in the head, one of his early Edvard Munch-esque paintings depicting the soul of a dying family friend leaving the man's body (clairvoyant of his future interests, perhaps?).
As the exhibition progresses, we see Ogbourne's research into the story of Wilhelm Kühne, a German physician in the 19th century who sought a method to develop, like a photograph, the residual image left on a person's eyes when they die.
At the centre of Kühne's experiments was the case of Erhard Gustav Reif, a German labourer who drowned his two sons in the summer of 1880 and was beheaded for his crime later that year. According to The Museum, Reif's dismembered eyes became - in the macabre narrative of optography - the basis for the first "human optograph" as Kühne set up an on-site laboratory at the murderer's execution.
Ogbourne has gone to great lengths to recreate the props and grisly implements associated with this experiment, from paintings of the execution tower to a piece-by-piece imagining of what this portable eye-lab would have looked like.
Exhibited in The Museum is a reproduction of the image that Kühne found on Reif's eye: what looks like an arch-shaped door, interrupted by a staircase. Was this the last thing Reif saw before his head fell via the guillotine?
Kühne dedicated himself to finding what the murderer might have seen in his last moments, meticulously exploring the execution site for a shape that might connect. He wasn't successful.
Ogbourne himself visited the town of Heidelberg to stake out the execution site. He's even built a strobe light into an old camera that "prints" the Reif image onto one's retina when we look through the shutter.
It's a show packed with material - drawings and paintings of retinas that look like portholes into the great beyond. Objects and documentaries narrate the various players in the optographic story.
But as we move through the show, led by the cryptic annotations that Ogbourne has adorned on the walls, we are invited to become "viewer-detectives". There's some kernel of fiction buried in the show and once we get the first whiff of it, the museum-like barrier of inscrutability starts to crumble.
"I'm a bit ambivalent about the whole idea of telling lies," says Ogbourne, who speaks in sentences that burrow their way haphazardly from one topic to the next. Just when the original thread seems to have been severed, he snaps us back to reality.