Real Focal Plane to Calculate 35efl

[AngelaDMerkel]

I am trying to set the focal plan size for film scans so that ScaleFactor35efl can be calculated automatically rather than setting the scale factor directly, but as far as I can tell, that calculation depends on knowing the resolution and focal plane size?

Is there a way to set FocalPlaneXSize and FocalPlaneYSize in millimetres and then have the final ScaleFactor35efl calculated from that? Film scans vary in resolution, so it's not possible to have a consistent process for setting the X and Y resolution, but it is possible to set a consistent focal plane area.

[StarGeek]

FocalPlaneXSize and FocalPlaneYSize are Canon specific tags and cannot be created, only edited in a Canon image that already has them.

If you look at the Composite tags page for ScaleFactor35efl, there are several tags that exiftool will combine to create the tag.

If you set FocalLength and FocalLengthIn35mmFormat, then exiftool will use those tags to calculate the ScaleFactor35efl. Those are the only two that you can set, as all the others are camera specific tags and can't be created.