Modifying Canon:LensType

[Archive]

[Originally posted by bogdan on 2009-12-30 16:34:34-08]

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

[Archive]

[Originally posted by exiftool on 2009-12-31 11:33:45-08]

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:

Code:

   Value below int8u minimum for Canon:LensType

- Phil

[Archive]

[Originally posted by bogdan on 2009-12-31 12:34:17-08]

Hi Phil,

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

Happy New Year,

Bogdan