It can be done using a camera obscura which was not only known in medieval times but long before that. In the latest documentary on the Shroud (I’ll try to dig up the name) how the image was produced using only technology, chemicals and other materials of the time of Da Vinci (who is the likely hoaxer) was clearly demonstrated. This process also produces the negative affect that we get with the Shroud when photographed.
As for testing the linen, all tests to date show it is no older than the middle ages. Whether Rome will allow further testing I don’t know but the cloth is not dated to 2000 years ago.
Also there is no documentary or tradition evidence prior to the middle ages.
BTW, did you know about how the the blood and serum stains were formed first, with the image - which is actually superficial, caused by a discoloration of the carbohydrate layer, which in turn was caused by a chemical change, that coats the topmost fibers of the threads - being second? We know this because in areas where there was blood, no traces of images were found: they acted to inhibit the image formation.
As for camera obscura (from
here):
SOUTH AFRICA: THE CAMERA OBSCURA, OPTICAL QUALITY CRYSTAL, UV RADIATION, SILVER NITRATE…AND URINE? LET US NOT FORGET THE CORPSE.
Let us not forget the Monks in Wonderland using a computer in the 12th century, either.
The event horizon of the Medieval Milieu has been badly crossed with this theory; a corpse hanging in the sun for several days at about a 15 feet distance from an optical quality quartz crystal inserted into the pinhole of
a giant Camera Obscura, while inside the Camera, again at a fifteen feet distance, a 14 feet long cloth hangs evenly covered with silver nitrate. Later on, to fix the image, the cloth is washed in a 5% diluted solution of ammonia or urine. Bingo. The first photo, a giant one at that, has been made, after the corpse has been turned upside down for a repeated performance for another seven days or so, the first position matching the second one perfectly.
Again, we hear the magic words; I quote “using materials that were available in the 13th century.” Never mind that an analytical and scientific thinking was not developed yet in the 13th century capable of bringing together the following process: a camera obscura not in use in the 13th century, the classics not yet translated, chemistry not yet invented, yet knowing the exact chemical properties of silver nitrate, knowing its light sensitive properties, without any knowledge of optics or the properties of light employing a bi-convex, finely ground quartz lens, knowing the properties of UV radiation before electromagnetism was known at all, knowing how to stabilize the image by ammonia or knowing the chemical properties of urine. Knowing that some day, from the negative through photography a positive image will be achieved. But how come, that not knowing the most evident fact, that corpses do not maintain rigor mortis or that they cannot hang for 14 days in the sun, or else you would not care to see what the camera obscura would bring in onto your canvas.
I think in this experiment
the Cheshire Cat truly was at work.
SCIENTIFIC DATA
The fact is, the South African study makes some other gross mistakes. The earliest lenses bi-convex in shape, where made for eyeglasses in the 14th century only. The theory of image formation by lenses was first studied by Sir Isaac Newton and Renee Descartes in the second half of the 17th century and particularly by Carl Friedrich Gauss in the 19th Century, who first introduced the idea of focal length. Giovanni Battista della Porta introduced in the 16th century the process of lens grinding and polishing which would have been absolutely necessary for the 13th century solarograph. Also in the 16th century, Daniel Barbaro of Venice mounted a convex eyeglass lens in the pinhole of a camera obscura for the first time in history to achieve a focused image on the opposite wall by bending the rays of light. The South African researcher also places the making of the Shroud-like camera obscura negative into Venice, but with a little three hundred years difference in the wrong time direction, way before the method was historically achieved.
What is even more remarkable is the mistake on this positive photograph ((
http://www.shroud.com/alice58.gif)), supposedly the result of the camera obscura experiment from South Africa. The corpse or body cast was supposed to hang fourteen, fifteen days out in the all day sun. As the sun moveS across the sky from morning till evening every day, it should evenly light the corpse without any effect of a light focus (direction of light). This photo shows a very easily visible, strong, directional light focus coming from the upper left side. The photo clearly is not the result of the process described.
The Turin Shroud (
right), shows absolutely no light focus (direction of light).