The tags of my photo is written by Lightroom, and zenphoto parse the iptc field in correct encoding, I think they are in UTF-8. I found form the web that LR set CodedCharacterSet to "UTF8" or "ESC % G" for the UTF-8 encoding, and zenphoto seem haven't handle it.

BTW, I feel that tagging using a list box on photo/album admin may lead to some performance problem when the tags growth. Since tag is loose description(VS keyword is strict one), i think a single line edit is enough, just like on this forum.

Tags may be either loose or strict.

Are you experiencning a performance problem with the list box? Why do you think a single line edit would be more efficient?

Zenphoto assumes ISO-8859-1 tag encoding. This seems the most common and so far as I know there is not a field that defines the encoding.

Actually I clean the tag regularly when it growth since I don't use tag on my gallery... It is just a feeling on the performance problem, but with a calculation, I mostly set 2 to 3 tag for my photo(though some are same set of tag), that become thousands of tag is quite easy. It is not a good idea to list all tag in album/photo edit page for choosing.

For encoding, my photo IPTC field CodedCharacterSet is set to "ESC % G", so it should be in UTF-8.
http://www.lightroomforums.net/showthread.php?t=2313

CodedCharacterSet does not appear in the IPTC Standard
Photo Metadata 2008

Maybe zenphoto could provide a option to enable import iptc tag or not. And, a option for choosing tag encoding.

Perhaps. Please open a ticket so that it is not forgotten.

Please do provide a ticket. I will implement the capability, but I need some images with UTF-8 encoding in them for testing. Attach them to the ticket.