Test your film camera's shutter

ShutterDoc measures how long your film camera's shutter really stays open, using your iPhone.

Shutters wear out. If you set the dial to 125 on an older camera, it might hold open for a hundredth of a second instead, with seemingly nothing amiss. ShutterDoc films the shutter at 240 frames a second and measures the light that comes through, telling you how truthful your camera's shutter speeds really are.

There are two ways to test speeds. The Quick Test can be performed handheld, in normal lighting conditions, and requires minimal setup. Point the phone, fire the shutter, and see each speed up to 1/60 on focal plane shutters and 1/125 on leaf shutters. It is quick enough to check a camera at a flea market before you buy it. The Full Test measures every speed from 1 second to 1/500, with the camera steady on a tripod or a stack of books, in an even light.

Both work on focal plane shutters, the kind in most SLRs and rangefinders, and on leaf shutters in the lens. ShutterDoc's readings have been checked against a dedicated phototransistor tester on six cameras of both kinds: a Nikon FE, Canon EOS-1N, Minolta X-370, Kiev 19, Tele-Rolleiflex and Kodak Retina.

For focal plane shutters there is also a capping test. Rather than a speed, it shows how evenly the light lands across the frame, and whether one band of it is getting less light than the rest. Fire the camera at least ten times at one speed, as fast as 1/1000, and ShutterDoc averages the firings into one map of the light across the gate.

The measurement happens on your phone. There is no account, and your video is never uploaded.

See how a test is done, on video.

Get ShutterDoc on the App Store, for iPhone.