A Poor Man's Stereo Microphotography
A few years ago I invested significant time and some money to travel several times to Hartford, Connecticut, to try and investigate the coat of arms my ancestors used in New England in the 17th century (1635 onward). In the State Archives was the only "archeological" evidence existing...a tiny and much damaged wax seal (below) on the will of the matriarch of the family, which supposedly preserved that very coat of arms pressed into the wax in 1669.
Using extreme magnification, which had to be done without touching the artifact, I could see it contained a lot of detail, and using my 35mm film camera I shot as many pictures as I could, since I wanted to continue to study this artifact once I got home, and making more day-long expeditions to Hartford was not practical.
I thought I had used my time well and had captured near perfect documentation of this tiny seal, less than the size of my fingernail. But once home and with the prints in hand, I realized that these two-dimensional images could only go so far in reconstructing the image in the wax. Without depth, the patches of color and shadow remained too ambiguous to get the job done with any certainty.
It was then that an experience from several years earlier came back to me. Aa an archeologist with the NY State Museum, I was doing some field survey accompanied by the staff geologist, Dr. Robert Dineen. As he walked around taking photographs of the salient topographical features, I noticed his peculiar behavior... he shot a picture, stepped a few feet to the left and took another picture of the same view.
When I asked what he was doing, he explained he was taking "stereo pictures". By creating two different images on film of the same view he was duplicating the stereo effect we obtain by seeing two different but compatible images with each of our two eyes.
And because he shot his images about four feet apart, he had created extremely enhanced stereo images, much like the standard stereo air photos geologists and others use all the time (below), where large distances separate the two viewpoints instead of the few inches that separate our eyes. He then viewed the prints using the same stereo viewers he used for the standard air photos. Having often used these stereo air photo pairs in my own research, I can attest to the fact that the exagerated 3-D effect, where objects appear many times taller than they really are, makes analysis of the "terrain" photographed very easy.
So I decided to try this same technique on the tiny "terrain" of the wax seal. I already was using a set of "close-up filters" (below) to allow me to get pictures as close as 1.5 inches from the object, and a small "high intensity" lamp to throw a raking light across the object to enhance shadows and therefore reveal the relief. (Note: this approach was used on a 35 mm film camera with a lens threaded to accept this type of filter, so adjustments may be made have to be made to match the camera you are using.)
The shadows can be recorded from several angles by rotating the item, or moving the light source, and most archives are willing to let you use the light and your camera if you tell them in advance what you are doing.
This is the system I used (above). First, set up your light source as low as possible to shine across the object. In my case I had it almost on the table to avoid the camera casting a shadow when to moved in close. Attach whatever close-up filters or lenses you need to get close enough to the object.
Now at this extreme proximity to the item, the images MUST be absolutely the same scale, or the stereo effect is lost. I accomplished this by getting as close to the object as I wished and focusing the camera manually. Then I did NOT touch the focus again. I moved slightly to the left, moved in until the object was in focus, and shot. Then I moved slightly to the right, moved in until the object was in focus again, and shot.
You want to avoid tilting the camera too much (the schematic above is exagerated) but merely be taking overhead shots from positions left and right of center. But depending on your distance from the object, a very slight tilt of the lens may be needed.
I spent an hour or so shooting in Hartford, and when I got the prints back home, I viewed them using a cheap little stereo air photo viewer, like the one above. It was just like being able tio spend as much time as I wanted with the object itself, and in fact, it was BETTER. Because the stereo images were slightly more separated than my eyes, the effect of 3-D was enhanced.
This allowed me to accurately separate the parts of the wax that were the original surface, created in 1669, from wax underlying that only appeared to be the true surface. And this allowed me to recreate not only the actual damaged seal as it existed in 1999, but also as it would have looked in 1669 (see below).
No doubt there are other ways of doing this, but I suspect they are not within the range of what most of us can get at, or afford. For me, this worked, and cost nothing, as I had the lamp, the camera, the filters and the stereo viewer already. Filters are about $25 and the viewers range from $20 to $150, with the cheapest ones working as well as any.
The key is matching the distance between lens and object in both views. A manual focus allows you to do this. It is hard to do it using any sort of measuring device as this often comes in contact with the item, which the archivist may object to. Digital cameras no doubt allow this same manual focus capability when taken out of auto mode.
Perhaps this is useful information.