Instance Property


The maximum exposure duration, in seconds, defined in the auto-exposure algorithm.


@property(nonatomic) CMTime activeMaxExposureDuration;


When you set a new session preset on your capture session or select a different activeFormat on your capture device, you can query or observe changes to activeMaxExposureDuration.

You can override this property at any time, to any value in the activeFormat property’s minExposureDuration and maxExposureDuration range. Changes are reflected immediately while the session is running, with no graph rebuilding. You can also set the property to kCMTimeInvalid to return to the default value. For example, one case in which you'd override the auto-exposure algorithm's maximum exposure duration is if you want shorter exposure than your frame rate. If you need to freeze motion by exposing for 1/40th of a second but still capture 30 frames a second, then a manual override is needed.

See Also

Managing Image Exposure


The length of time over which exposure takes place.

- setExposureModeCustomWithDuration:ISO:completionHandler:

Locks the exposure duration and ISO at the specified values.


The metered exposure level's offset from the target exposure value, in EV units.


Bias applied to the target exposure value, in EV units.


The minimum supported exposure bias, in EV units.


The maximum supported exposure bias, in EV units.

- setExposureTargetBias:completionHandler:

Sets the bias to be applied to the target exposure value.


A special constant representing the current exposure bias value.


A special constant representing the current exposure duration setting.

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