How Leica Measured Shutter Speeds to the Millisecond with the Naked Eye

Alabama-based photographer and engineer Destin Sandin of the YouTube channel SmarterEveryDay recently visited KameraStore in Finland. Sandin, whose videos deliver in-depth technical information in an entertaining and understandable way, learned about Kamerastore’s specialized restoration and testing process, which includes using period-appropriate machinery.

Beyond repairing and testing cameras, Kamerastore offers the world’s only camera mechanics training program and technician training school. It’s home to equipment and machines that would excite any photography enthusiast, especially one as interested in the technical aspects as Sandin.

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Sandin’s latest video goes behind the scenes at Kamerastore, including a look at a very special Leica testing machine from the 1930s. The device allows a trained technician, like Ari at Kamerastore, to calibrate an old Leica curtain-type focal plane camera shutter. The machine relies upon a rolling shutter-like effect that allows a trained technician to calibrate a shutter by eye.

Leica’s first commercially available 35mm camera, the Leica 1(A), hit store shelves in 1925. It, and later Leica cameras, were among the best on the market. Like many later cameras, early Leica models included a shutter speed dial on top. This mechanical dial allowed the photographer to select a shutter speed, like 1/1,000 second, for example. The shutter speed dial must be precisely calibrated to the actual speed of the shutter.

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If the photographer selects the 1/1,000 second shutter speed, that means the shutter is open and the film is exposed to light for just one millisecond. Leica engineers needed to tune its cameras to ensure that the shutter was open for the expected duration, with extreme precision. That’s where the special calibration machine Sandin saw in Finland comes in.

The machine measures a millisecond mechanically. Accompanying the machine is an original Leica repair manual — in German, of course — that includes diagrams showing precisely what the shutter should look like through the machine at different shutter speeds. At various rotational rates, a correctly-calibrated shutter will produce differently-curved lines.

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Not satisfied to leave such cool technology behind in Finland, upon his return to the U.S., Sandin recreated the incredible machine using a drill, ketchup bottle, and magic marker. Combined with a phantom high-speed camera and extremely bright Nanolux light that doesn’t flicker, Sandin can use the high-speed camera to view lines on the ketchup bottle as it spins behind the camera on a drill.

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Using an additive animation technique, it’s possible to see the curved lines like what was visible using the dedicated Leica machine. While a ketchup bottle with marker lines may seem crude, Sandin’s setup is sophisticated. Leica technicians performed these measurements with a single machine and the naked eye. Kamerastore’s skilled technicians still do.

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Another piece of the puzzle is ensuring that the machine’s rotation, or ketchup bottle in Sandin’s case, matches up with a standard speed. Otherwise, the achieved shutter speed measurements may be incorrect. The Leica machine uses aliasing, much like a record player, to allow the user to dial in a precise benchmark speed. It’s an incredible machine.

Image credits: SmarterEveryDay, Kamerastore