Exif 0xa404 41988 DigitalZoomRatio

[Hervé]

Hello,
The camera of my Samsung Galaxy S23 Ultra Smartphone has 4 lenses named 0.6 1 3 and 10.
The lens x1 has a focal length of 6.3 mm.
In addition, like most cameras, you can zoom by spreading 2 fingers on the screen; I expect the Exif DigitalZoomRatio field to contain the value of this manual zoom.
However, if I use the x3 lens without zooming with my fingers, the Exif DigitalZoomRatio field contains 3 and the focal length 7,9 mm !
I was expecting a focal length of 6.3 x 3 = 18.9 mm and a DigitalZoomRatio = 1.

How should the Exif DigitalZoomRatio field be interpreted ?

Thank you in advance for your expertise.

[Phil Harvey]

The EXIF specification gives this description of the tag:

This tag indicates the digital zoom ratio when the image was shot. If the numerator of the recorded value is 0, this indicates that digital zoom was not used.

- Phil

[Hervé]

Thanks, that's why I expected to find there the digital zoom ratio.
When I use the X3 lens without zooming manually the value should then be 1 or 0.