Stereoscopes and Archaeology

I’ve just started my PhD, which means this blog is about to get a LOT more active! If you’re curious about what my PhD is in, you can check out the longer description here. For now, I’m looking at finding a practical, portable, and affordable way to create 3D models of small, reflective, and translucent objects (using beads as a case study, because they fit perfectly). You can check out the reasoning in the longer description, too.

But as a result of having just started, I am in the middle of a LOT of reading, which means I have a lot to talk about, at least theoretically speaking. So I’m going to start doing more of these posts, talking about what I’ve read, what I’ve learned, and why it’s important for not just my research, but bead studies and archaeology in general. Hopefully you guys can benefit from some of this, and at the very least, it’ll help me internalise what it is I’m reading.

So this week, I didn’t do crazy amount of reading because most of the week was running around taking care of logistics – picking up residence permits, filling out loan paperwork, etc., etc., etc.

But I did read something really cool, and it had to do with using stereoscopic images as a way of viewing enhanced macro photographs and even semi-3D images (Campana, 1977). Stereoscopes are those contraptions you’ve probably seen from the 1800s that look like a View-Master we all know and love from childhood, just bigger (because that’s exactly what it is). You place a card with two slightly offset images in the holder and look through the lenses. Because the images are slightly offset, when you look through the lenses, the image appears to be 3-dimensional.

Stereoscope (from https://upload.wikimedia.org/wikipedia/commons/f/f6/Holmes_stereoscope.jpg)

19th century stereoscope

In the 1970s, this was one really effective way of making 3D images in archaeology (1977, 435). Taking photos from a microscope or using a macro lens was really difficult to preserve in publication. The depth of field is generally quite small, and while our human eyes can account for it and adjust accordingly (at least to some degree), cameras really couldn’t (and still aren’t great at it). So, at least in the 1970s, creating stereophotograph pairs was one fairly simple way of preserving photomacrographs or photomicrographs for others to view (Ibid). It also helped in cases where a researcher was looking at various collections in different locations, because you could preserve the images from your first collection and bring them to the second for comparison (Ibid).

Stereo-photomacrographs, as these images are called (or stereo-photomicrographs when created from microscopes) are created by taking two separate photographs where the lenses are offset by 6.5cm (Ibid, 436). This is the average distance between human eyes, so it needs to be the distance offset for these photographs. With photomacrographs, it gets a little dicier, because you’re so close to the object. For these photos, you offset the image by 15° instead (Ibid).

You can use two cameras simultaneously to take the photos, but with macro photos (or microphotos), you can’t really place two cameras close enough together to get the right image. So instead, you use the same camera and just move it (Ibid).

Photomacrographs have a better depth of field than micrographs, because you can control more of the functionalities of the lens. So up to a certain magnification, photomacrographs are actually better than photomicrographs.

To view the images, you can build a lens system similar to the stereoscopes used in the 19th century, or you could just find one and use it. According to the main article I was reading (Ibid, 439), you can also train yourself to see the images without a stereoscope, but I don’t know if I’ll ever be able to do that.

Not only was this all really fascinating to read anyway, it was particularly fascinating having just come from working in a museum specialising in the 19th century and particularly working with a stereoscope and a set of three images. I never really would have guessed that they could be used as a precursor to computerised models, but now that I’ve seen it and read it, it makes complete sense. And now I just really want to try it, despite having zero access to stereoscopes.

There are probably a certain number of you saying something along the lines of “this is really cool, but what’s the point? Why use these images?”

Good question. The main point in the 1970s was to view objects in different ways, with different depths and lighting than the human eye naturally did. Doing so allows us to see things like wear patterns, designs, or cut marks on objects that we may not be able to see with the naked eye. Our eyes are really good at adjusting to different circumstances, so they can often block out things that we actually DO want to see. Creating stereoscopic images provide a depth of field to the objects that often allowed for more clarity and a stronger ability to see those thing we might not otherwise see.

Polychrome 1

When it comes to macro photography, these lenses allow us to zoom into objects that are quite small, or zoom into areas our eyes can’t see simply due to the size of what we’re trying to look at. I’ve used this with beads quite a lot, and have posted a number of the results on this blog (like the image above). But I’ve never tried stereo-photomacrographs before, and I’m quite keen to try, if only could find a viewer.

 

Everything I talk about in this post comes from the following source as well as personal experience in museums:

Campana, Douglas. 1977. Making Stereo-Photomacrographs for Archaeological Studies. Journal of Field Archaeology. 4, 435-440.

Stereoscope image from https://upload.wikimedia.org/wikipedia/commons/f/f6/Holmes_stereoscope.jpg

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About Heather Christie

Heather is an archaeologist, photographer, and writer whose research focuses on beads and bead trade, particularly in a maritime sense. She's currently working working on a PhD in Digital Design (focusing on heritage visualisation) at the Glasgow School of Art.
This entry was posted in Lab Notes, Technologies and tagged , , , , , . Bookmark the permalink.

3 Responses to Stereoscopes and Archaeology

  1. simon j cook says:

    Congratulations on starting the PhD, Heather! I’m happy at the thought of many more posts here on your blog.

  2. Abhijit says:

    Very nice… I really liked your blog..😄

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