I wanted to build an awesome place for people to discuss module specific issues, but I don't have any more time
for this, and there are much better places to discuss Perl-related issues. I'd recommend asking your question on Stack Overflow or
on Perl Monks.
If you are looking for a Perl tutorial or Perl-related news,
I hope these links will serve you well.
If you use the -v2 option you will see the following
message (among lots of others):
"Not enough values specified (4 required) for Nikon:Lens"
It is the -n option that is causing you the problem,
not -if. The Nikon:Lens tag must be converted to
numerical form when writing, and the -n disables
this conversion so the tag is not written because the input
string is in the wrong format.
Please let me know if you have any more problems.
P.S. You get points for trying this with the most recent ExifTool
version before posting this.