Photo credit: Catchoooo / Reddit
Before smartwatches, and even calculator watches, there was he Tessina. It's essentially a 35mm camera patented by Austrian chemical engineer Dr. Rudolph Steineck in Lugano Switzerland, and manufactured by Siegrist in Grenchen Switzerland. First introduced in 1957 and distributed by Steineck's company Concava S.A, it remained in production up to 1996. The watch takes 14x21 mm pictures on standard 35mm film (loaded into a special cassette), making it one of the few sub-miniature cameras to use the format. Each one is hand assembled from more than two hundred precision parts, and designed tot take 100,000-pictures. Click here to view more pictures of the Tessina. Continue reading for a video showing how the controls work and more information.
It comes equipped with a very small (2.5x2x1 inch) twin lens reflex, with two 25 mm f/2.8 Tessinon lenses - one for taking the picture, the other for viewing on a tiny ground-glass focusing screen on top of the camera. A 45° mirror is employed to bend incoming light onto the film, which lies along the bottom of the camera rather than the back to save space. Apertures are continuously variable down to f/22, and shutter speeds range from 1/2 to 1/500, and B. The Tessina 35, Tessina L can focus down to 9 inches, Tessina Automatic 35mm to 12 inches. The film is advanced via a clockwork master spring built into the takeup spool, with a pullout winder like the crown on a wristwatch. Each winding can last up to 8 exposures.