Photos shot with the wet-plate camera onboard any U-2 plane flying around the world is shipped (via FedEx) back to the base in California to be developed and analyzed. The images are shot on 250-pound rolls containing 10,500 feet of 6-inch-wide film.
The 1950s camera, combined with the U-2’s altitude, provides formidable photo capabilities: it can cover every inch of an entire country in a single mission. Photographing nearly all of California takes just four hours, and the planes are used to photograph the entirety of Afghanistan about once every month.
Using loupes and microscopes, analysts can distinguish objects in the resulting photos that are just 8 inches apart on the ground — enough resolution to read the numbers on the wings of a parked airplane.
While the military is working on computer technologies to help analyze scans of the film, the analog processes themselves aren’t going anywhere (for now).
“[W]et-film cameras still outperform other surveillance gear by delivering crisp images from above 70,000 feet, where the pilot can see land for 250 miles in any direction,” the Wall Street Journal writes.
“It works, and that’s why it’s still around,” says Sr. Airman Taylor Workman in the documentary.
In the magic of my mind, this raises a couple of interesting questions:
1. What sort of a lens permits that sort of resolution at 70,000 feet? (And a secondary question: what sort of grain/resolution does the film have?)
2. If the wet film solution outperforms other gear, that would imply that digital solutions are not as good, no?
1. A large, heavy and expensive one. I think one of our members posted a picture of the camera from a U2 a while back. It was on display in a museum somewhere. Unfortunately, I can't find that image now or I would post a link. But I remember that everything about the camera was large.
2. I guess a digital sensor which matches the resolution of a 6-inch wide strip of film is going to be pretty big, and there is a limit to how large you can make a wafer of silicon. And maybe a film camera is more rugged - better at dealing with variations of temperature and pressure, electromagnetic interference in the upper atmosphere and the occasional SAM missile exploding nearby.
a question of my own:
3. Does a photo reconnaissance camera create a series of conventional rectangular images as the plane flies along, or does it expose a continuous strip, like a photo-finish camera at a racing track?