Hi,
a picture file is croped from ImageSize: 5152x2904 to ImageSize: 640x480
All metadata are copied, but how to update crop factor? field of view?
I'm happy with this formula, which is the inverse ratio of the diagonals: ird = SQRT( ( 5152 ² + 2904 ² ) / ( 640 ² + 480 ² ) ) = 6.978...
Then read equivalent focal length
exiftool -FocalLengthIn35mmFormat filename.jpg
Focal Length In 35mm Format : 150 mm
calculate 150 * ird = 150 * 6.978... = 1046.80...
Apply
exiftool -FocalLengthIn35mmFormat=1046.80 filename.jpg
Then -FOV (field of view) is updated, and maybe some others.
The follogwing fields are updated (and maybe some others):
-FocalLengthIn35mmFormat
-ScaleFactor35efl
-CircleOfConfusion
-FOV
-FocalLength35efl
-HyperfocalDistance
field | from | to |
-FocalLengthIn35mmFormat | 150 mm | 1047 mm |
-ScaleFactor35efl | 4.4 | 30.8 |
-CircleOfConfusion | 0.007 mm | 0.001 mm |
-FOV | 13.7 deg | 2.0 deg |
-FocalLength35efl | 34.0 mm (35 mm equivalent: 150.0 mm) | 34.0 mm (35 mm equivalent: 1047.0 mm) |
-HyperfocalDistance | 60.62 m | 423.13 m |
You can check the Composite tags page (https://exiftool.org/TagNames/Composite.html) to see what these tags are derived from.
Thank you very much !
By the way, I made a mistake in my ird value calculation. But my explaination is still ok.