On May 4, 2006, at 9:48 AM, John Francis wrote:
Short answer(1): The lens ID code.
Short answer(2): Nothing.
If you select the appropriate settings for DNG, the Pentax private
data
in the MakerNote tag will get copied to the DNG file, so no
information
is lost. The real problem is that there is no standard EXIF tag
scheme
to identify the lens. This means that to get at that information, a
program must either:
o Know how to find the information in the .PEF
This is what the Pentax browser and Photo Laboratory do.
That's why they can show you the name of the lens you used.
or
o Know how to find the information in the copy of the MakerNote
tag, and/or in other non-EXIF tags created during RAW
conversion.
While the information isn't lost, that doesn't help you all that much
if you don't have software that can extract the information. But at
least it would be possible to put together a little utility to extract
the lens ID code, and translate it to the appropriate lens nae string.
Current versions of DNG Converter and Camera Raw preserve this data.
Bridge retrieves it and displays it correctly, when present, in the
Metadata panel under the Camera Data (Exif) section.
EG: http://homepage.mac.com/godders/lens-data-in-bridge.jpg
Godfrey
