Posted 6 years ago
Yep … pre-1900 photographers needed a little assistance to figure out how to make good pictures; and it wasn’t all that easy. There were an amazing variety of devices and methods to measure light from the early 1880s on. Here are two brass examples in my collection.
On the left is Decoudin’s visual meter (patented 1887) with its original cardboard box. It was placed against a view camera’s focusing screen. While under a dark cloth, the photographer turned a center knob until three small holes in an oval slot appeared to disappear while a larger hole remained visible, etc. An exposure table is then referenced in the reverse side and the camera's shutter and other mechanics adjusted.
Watkin’s Standard Meter of 1890 is a nicely machined tubular body with lots of levers and scales – very cool looking. It has a compartment in one end to hold a roll of sensitive paper that is exposed through a hole in an end cap. The time it took for the paper to darken is compared to a sample. Elapsed time is then measured by swinging another end cap attached to a chain; which is designed as a one-second pendulum. Exposure calculation involved manipulating the adjustable levers and scales. In all honesty, I’ve yet to figure out how this works.
Although I like antique equipment and my first 35mm cameras were completely manual, it sure is nice that today’s cameras automatically adjust themselves!