I am using Nikon D3500 but the question may be of a general nature. I understand that the Camera measures distance between the subject in focus and the Camera for deciding the flash light requirements and other parameters. Is this ACTUAL distance information displayed on the screen in live view or in the view finder when we put the shutter release button half way down.

(An illustrative image will be more helpful in understanding)

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    Subject distance is not the controlling factor for flash. TTL flash control fires the flash then cuts it off when it decides enough light has been seen. If the subject is too far away, the flash reaches it's full energy limit and ends with insufficient light. – user10216038 Aug 2 '20 at 16:49

It's saved in the exif data when the photograph is taken, as Focus Distance, but I know of no way to access it directly from the camera, either before or after taking the shot.

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    I think this does not answer the question: The question is about how to view the 'actual distance' on a certain camera in the moment of the shoot. It is not about how to retrieve the information after the image was taken. – quiliup Aug 2 '20 at 11:40
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    @quiliup - I could have just written "This cannot be done." with no further information at all. Would that have better satisfied your criterion for it being "an answer"? – Tetsujin Aug 2 '20 at 11:55
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    The focus distance in the Exif data is often seriously incorrect, especially in zoom lenses and/or internal focusing lenses, which are continuously modifying the lens geometry. My complaint is that it seriously affects the TTL BL flash accuracy. My site has charts of this for of some Nikon lenses, at scantips.com/lights/ttlbl-d.html#3 – WayneF Aug 2 '20 at 14:01
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    @WayneF - I was unaware of the BL distance factor. This seems odd to me as the lens distance and flash distance would only be the same for on-camera flash. – user10216038 Aug 2 '20 at 17:09
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    Yes, same distances for camera direct flash. But Nikon TTL BL flash mode (and Canon has a version) uses the reported lens distance to prevent overexposure of direct flash metering a dark background (beyond flash range) that would commonly cause overexposure (trying to brighten the dark background). That seems reasonable, except that it fails when the actual distance is more than the lens distance reports, which judges the flash power should be less causing actual underexposure (No lens correction is attempted for metered underexposure). My link above has examples. – WayneF Aug 2 '20 at 19:00

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