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# quickTimeMetadataKeyCameraLensIrisFNumber

A value of type kCMMetadataBaseDataType_UTF8 indicating measure of the amount of light transmitted through the lens. It is the focal length divided by the effective lens aperture diameter (e.g. “F2.8” or “2.8”).

```
static let quickTimeMetadataKeyCameraLensIrisFNumber: AVMetadataKey
```

## Discussion

This is track-level metadata for video track that is associated with the camera.

---

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