Modifying Canon:LensType

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Posted on 2009-12-30 16:34:34-08 by bogdan

Hi Phil,

As you know, Canon EOS 7D (for example) raw file contains two LensType tags inside Makernotes (older cameras had one tag only).
If I modify this tag(s):
exiftool -n -canon:lenstype=150 myfile.cr2
-i get expected result (both of two tags are changed).

But, if I wish to set this tag to "Unknown(-1)" lens:
exiftool -n -canon:lenstype=-1 myfile.cr2
-then only one tag (22dec) is changed to -1, while another (239dec) doesn't change.

Any idea? Thanks for answering.
Bogdan

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Posted on 2009-12-31 11:33:45-08 by exiftool in response to 12047

Re: Modifying Canon:LensType

Hi Bogdan,

The reason for this is that only one of the LensType tags is capable of storing a signed integer. LensType 22dec is a 16-bit signed integer, while LensType 239dec is an 8-bit unsigned integer.

Sometimes the -v3 option can help debug problems like this. Here you get a bunch of messages like this from the various Canon LensType tags which can't be written:

Value below int8u minimum for Canon:LensType

- Phil

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Posted on 2009-12-31 12:34:17-08 by bogdan in response to 12052

Re: Modifying Canon:LensType

Hi Phil,

Thanks for clarifying.. this also explains some other things I wondered about.

Happy New Year,
Bogdan

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