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# focalLength(at:error:)

Gets the focal length.

```
func focalLength(at time: CMTime, error: NSErrorPointer) -> Double
```

## Parameters

`time`

Specified time, expressed as a <doc://com.apple.documentation/documentation/CoreMedia/CMTime>, to retrieve the matrix value.

`error`

Description of the problem if you are unable to retrieve the value.

## Return Value

The value of the focal length.

---

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