One of the characteristics of early photographic processes is that they are slow. This limits their use for indoor portraiture unless a strong artificial light source is available, or a camera with a very fast lens. Regarding the latter, I came across an interesting camera design that gives a fast working aperture of f/1.7 by using a concave focusing mirror rather than a conventional lens. This camera, invented by Alexander Wolcott and John Johnson, was awarded the first U.S. photographic patent in May 1840, patent number 1582.
The Wolcott camera was designed for making Daguerreotypes. It consists of a simple box with an aperture at one end and a mirror at the other. Working on the same principle as a reflecting telescope, the image is formed on a plate-holder about one quarter along the length of the box. The fast aperture of the camera reduced the time for Daguerreotype exposures from tens of minutes to two minutes or so, making the process practical for portraiture. On the downside, the camera was cumbersome and required a large mirror to make photographs of a reasonable size. A mirror 7 inches in diameter produced an image just 2 inches square.
I first came across the Wolcott camera at a Royal Photographic Society meeting in July 2013 where Roger Smith, a member of the Scientific Instrument Society, showed a full-size replica of the camera. My laser-cut version of the camera is much smaller, using a 3 inch diameter focusing mirror and producing images about 1 inch square. I followed the general scheme of Wolcott’s design, with a sliding platform for the plate holder that is moved in and out to achieve focus. Two hatches are cut in the top plate, one to view the plate holder during focusing and the other to provide access to the mirror for cleaning.
In use, the camera is placed on its baseplate and focused. The whole camera is then moved to a darkroom (or dark box if working in the field) and loaded with a plate. The plate is exposed by removing a simple wooden plug at the front of the camera, and then the whole camera is again returned to the darkroom to process the plate. So far I have achieved good results using both collodion on blackened aluminium plate (‘tintype’) and paper negatives. Indeed, the camera is sufficiently fast to allow in-camera exposure of cyanotypes. To do this, sensitised paper is placed in the plate holder and exposed for several minutes. The paper negative is then removed and scanned directly on a flat-bed scanner, without any development. When inverted and toned in Photoshop, a surprisingly detailed image can be obtained.
Laser cutting plans for the camera can be downloaded below as an Adobe Illustrator file, and a SketchUp model is also available:
The mirror and brass knobs were purchased on eBay for a few pounds. The only other material required is some thin plasticard to make the edges of the plate holder. The following video shows the camera in action.