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10-17-2008, 06:13 AM   #1
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Pentax Lens Tagsin EXIF Data

I was pointed towards the following page as part of a discussion on another forum which was instigated by a thread on this forum:

Pentax Tags

These folks, (physics students at Queens University in Toronto, judging by the URL) are decoding the various data fields in the EXIF data.
What I found interesting was the Pentax LensType Values section, about 1/3 of the way down.
Prefacing it they say:
"Note that newer series numbers may not always be properly identified by cameras running older firmware versions."

Does this mean that the camera stores lens type information in an internal data base, which, if not updated through firmware makes the camera unable to properly recognize lenses that were marketed after the camera was built?

It appears that there are two ways (in Pentax's world) of identifying the lens used. One is in the camera's firmware, the other in external software (PhotoME, etc).

10-17-2008, 06:19 AM   #2
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QuoteOriginally posted by Wheatfield Quote
I was pointed towards the following page as part of a discussion on another forum which was instigated by a thread on this forum:

Pentax Tags

These folks, (physics students at Queens University in Toronto, judging by the URL) are decoding the various data fields in the EXIF data.
What I found interesting was the Pentax LensType Values section, about 1/3 of the way down.
Prefacing it they say:
"Note that newer series numbers may not always be properly identified by cameras running older firmware versions."

Does this mean that the camera stores lens type information in an internal data base, which, if not updated through firmware makes the camera unable to properly recognize lenses that were marketed after the camera was built?

It appears that there are two ways (in Pentax's world) of identifying the lens used. One is in the camera's firmware, the other in external software (PhotoME, etc).
Perhaps not exactly the same question, but phrased in other words.

Does the EXIF data embedded in a camera generated JPEG ever contain the "Textual description of the lens" (eg FA77 Limited etc) or is this info deduced by image processing software from the numeric lens-id?
10-17-2008, 06:23 AM   #3
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The EXIF data only contains a numeric ID, supplied by the lens to the camera. It is up to each software to translate that into a textual description.

Note that the ID codes are *not* unique, especially for 3rd-party lens. For example, my Sigma 17-70 is often reported as "Tamron 35-90mm F4 or various SIGMA models".
10-17-2008, 06:26 AM   #4
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Hi,
I don't think there is any textual information coded in the exif data. The lens ID is there though...
So I do think, as Tomtor suspected, that this lens ID can sometimes be interpreted wrong by the image processing software(s).
In the case of Exiftool and PhotoME, the correspondance between Lens ID and textual info on lenses is updated whenever someone comes across a "new" lens or an incorrect association.

François

10-17-2008, 11:49 AM   #5
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Queen's University is in Kingston, about 250 km east of Toronto.
10-17-2008, 12:30 PM   #6
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QuoteOriginally posted by sewebster Quote
Queen's University is in Kingston, about 250 km east of Toronto.
Figures. It's all Toronto west of Superior.....
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