Question

Problem: I can set the exposureMode property of AVCaptureDevice, but it does not stay locked.

Here is my code:

NSArray *devices = [AVCaptureDevice devices];
NSError *error;
for (AVCaptureDevice *device in devices) {
    if (([device hasMediaType:AVMediaTypeVideo]) && 
        ([device position] == AVCaptureDevicePositionBack) ) {
        if ([device isExposureModeSupported:AVCaptureExposureModeLocked]) {
            device.exposureMode = AVCaptureExposureModeLocked;
            NSLog(@"Exposure locked");
        }
        [device unlockForConfiguration];
    }
}

I take 4 pictures one after another programmatically. The exposure stays locked in the first two pictures, but becomes unlocked in the last two. This happens when before locking the exposure I tap on a dark portion of the camera view so that part of the picture is over-exposed. It looks like iOS decides to do auto-exposure and override the exposure lock mode when the picture is overexposed.

thanks for the help,

Answer 1

this problem seem to have been fixed in iOS 5.