Hi thanks again for your reply. Just a few last points of clarification.
1) I understand I shouldn't coopt the EXIF fields (camera maker,camera model etc)because these fields could be overwritten by the embedded image metadata on upload.
I'm less clear about whether this also applies to the location/city/state/country/credit/copyright fields, not least because these fields - in contrast to the EXIF fields - are editable in the Administration backend.
So to double confirm, are you saying that the location/city/state/country/credit/copyright zenphoto fields will be overwritten for an image, if the uploaded image has IPTC metadata embedded in its header? I can't test this because I have no tools for setting an image's iptc metadata.
If this is the case, why are these fields editable in the backend whereas the EXIF fields are not?
2) I've looked further into the custom data filter as it sounds interesting. The ability to create new fields would as you say get around this issue.
I've installed the filter-custom-data plugin, and made sure it is enabled in the backend. But I don't see any difference when I edit and save or upload a new image? I was expecting to see some new fields?? I've assumed I don't have to edit admin-edit.php as that's already done for me?? i'm on version 1.2.6.
Can you clarify what it is I should be seeing, where and what I might be missing?
Much appreciated
chw