My little typewriter stereoscope

Well the other day I came across this beautiful item on the flea market in basel: a stereoscope produced by Unis, Paris. 

Stereoscopy is almost as old as photography itself. Even before the advent of photography, cardboard drawings were used to create threedimensional pictures.

With my (well I admit I bought two) machines came several slides. Here you see a man sitting by the seaside, a nice photo I must say. I only show one half of the slide here, the second half being an almost identical picture, but taken from a slightly different angle, just so far apart as to simulate the distance between our eyes. When looked at separately, our brain then composes one three dimensional image from the two 2-D photos.

View on the lake through the woods, another slide included in the package. Above, photographed through the stereoscope, below the full picture, actually closer to the real effect when looking through the glasses.

Ok, so, my first thought was: I need to produce typewriter slides for this machine! Said an done. Transparent film for overhead projectors and printable with inkjet were readily available at the local store, further I had to invest in a new colour cartridge. I did some research on how to produce the pictures which then should go on the transparent sheet. 

Here you see the composite picture which resulted from taking two pictures, done on a tripod, then calculated the stereo baseline (1/30th of the distance from lens to object, so, in my case, 3-4 cm) and moved the tripod sideways accordingly (no macro slide at hand, would come in handy) for the second picture. Here you see the overlapping photos which show the side movement corresponding to the different angle of our left and right eyes.

I did this overlay in order to adjust the vertical position, which must be precisely the same line for both photos. I think the horizontal distance doesn't need to be superprecise: 3 or 4 cm hardly matter, our brain is clever enough to figure it out. The end result however is the two photos side by side.

Here is the final sheet before cutting.

close-ups, and one single slide.

There we go, first test, and it worked right away! The 3D-effect is real, I was happily surprised. It's physics, baby!

A look through the lens - can't really simulate the 3D effect in this post, although there would be ways... (maybe some other time)

Dr. S. spending the rest of the afternoon gazing at typewriters in the world's first mini-typewriter exhibition!