exif:ISO - field limitations?

[Beholder3]

Hi,
I just looked at two files (.cr2 and JPG) from a Canon 5D3 shot at ISO 102.400.
There the exif:ISO shows up as "65535". At the same time the makernotes:baseISO is correctly "102400".
Values below this work nicely.

Is this really written wrong into the files? Or is there as misunderstanding from exiftool?

[Alan Clifford]

That looks like a 16 bit number has max'ed out to me.

[Phil Harvey]

This is the way that the EXIF spec stores values larger than a 16-bit integer.  The added some new 32-bit ISO tags to store the value in this case.

- Phil