This 24-inch camera was built to spy from 80,000 feet

Photographers usually discuss focal length in millimeters. But the San Diego Air & Space Museum’s newly unpacked reconnaissance camera is identified in inches: 24 of them, or roughly 610mm. According to the museum, an even longer 48-inch version followed. 

The camera was part of a cache of unused 1960s-era equipment supplied with the museum’s Lockheed A-12, the CIA’s Mach 3 reconnaissance aircraft and the predecessor to the SR-71 Blackbird. The video is nearly 20 minutes long and begins with substantial background on the A-12 (it is an aviation channel, after all) so photographers may want to jump to the 11:47 mark, where the museum gets into the cameras and how they were used. 

In the video, host Gordon Permann walks through some of the challenges of making a sharp photograph from about 80,000 feet while traveling at roughly 2500 mph. The ground would move hundreds of feet beneath the aircraft during an exposure, resulting in a blurred image. Making matters worse, neither the aircraft nor the terrain would necessarily be level. The solution was motion compensation: the camera itself would “skew,” or make a small movement as its aperture opened, counteracting image smear.

Another fascinating feature is simply how much film these systems used. Permann first shows the standard film canister used in reconnaissance aircraft from the 1950s through the 1990s, which he says held roughly 1200 feet of film. But the A-12 and SR-71 Blackbird needed still more film, so a larger canister was made. The museum has one of those, too, which Permann lifts in the video. He explains that the larger camera used a five-inch-wide film strip, with around 4.5 inches of usable image area. Each individual frame measured about six feet long.

Permann says the system could image more than 100,000 square miles in a single hour, capturing huge swathes of land or sea at once. He also recounts a Blackbird making a turn with its camera running and pointed out to sea. When the film was developed, analysts reportedly spotted a U.S. destroyer on the horizon, 94 miles away, and were able to identify the ship’s type despite the distance.

A separate, still-factory-wrapped camera in another crate is the real mystery: its 1953 date predates the A-12 project by six years, so it couldn’t have come from a Blackbird-family aircraft. The museum is seeking the public’s help to identify what airplane it may have been used on, so anyone with a theory can head to the video and share it in the comments.

Want to stay up to date on the latest product news and releases? Add DPReview as a preferred source to ensure our independent journalism makes it to the top of your Google search results.