I gave you an example of how to convert UTF8 tags to Latin1, but you need ExifTool 6.90 to do it. If you want to convert when copying to another file, just use a different filename as the source in the -tagsfromfile option.

Thinking about this a bit more carefully: There is no way to throw out non-Latin1 characters, because all byte values 0-255 correspond to a valid Latin1 character.

As I said, the Latin1 escape sequence is not simple. "ESC,A", "ESC-A", "ESC.A" and "ESC/A" in CodedCharacterSet will designate Latin1 for graphics character set 0 through 3 respectively, but then you have to invoke the appropriate set through an ISO 2022 escape sequence in the text itself, otherwise the CodedCharacterSet's don't get used. This is a real pain, and no software will decode this properly.

Did I mention that IPTC really sucks when it comes to coded characters?

- Phil