Wow.... focus distance reported in EXIF???

Started Nov 24, 2009 | Discussions thread
hotsnow New Member • Posts: 1
Re: Wow.... focus distance reported in EXIF???

I think Canon is only recording the FocusDistanceLower and Upper Info which only represents the position/range where the lens was focused. There is no real distance measure. Here an example:

I took a picture from a mountain very far away:

F Number : 8.0
Focal Length : 18.0 mm
Hyperfocal Distance : 2.14 m
Focus Distance Upper : 4.92
Focus Distance Lower : 3.06

Hmmm... why is the "Focus Distance Upper" not inf? The answer is the lens didn't need to focus farer away because the Hyperfocal Distance is 2.14m -> if you focus between 3.06m and 4.92m the subject is also in focus. If you change to manual focus and focus to infinity, then change back to auto focus and take the same picture again the Focus Distance Upper will be "inf"

Conclusion:

If the "Focus Distance Lower" is higher as the "Hyperfocal Distance" you only know, that the subject is somewhere between Focus Distance Lower and infinity.

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