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# exposureTargetBias

The bias to apply to the target exposure value, in exposure value (EV) units.

```
var exposureTargetBias: Float { get }
```

## Discussion

When the device exposure mode is [`AVCaptureDevice.ExposureMode.continuousAutoExposure`](/documentation/AVFoundation/AVCaptureDevice/ExposureMode-swift.enum/continuousAutoExposure) or [`AVCaptureDevice.ExposureMode.locked`](/documentation/AVFoundation/AVCaptureDevice/ExposureMode-swift.enum/locked), the bias affects both metering ([`exposureTargetOffset`](/documentation/AVFoundation/AVCaptureDevice/exposureTargetOffset)), and the actual exposure level ([`exposureDuration`](/documentation/AVFoundation/AVCaptureDevice/exposureDuration) and [`iso`](/documentation/AVFoundation/AVCaptureDevice/iso)).  When the exposure mode is [`AVCaptureDevice.ExposureMode.custom`](/documentation/AVFoundation/AVCaptureDevice/ExposureMode-swift.enum/custom), it only affects metering.

This property is key-value observable.

---

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