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06-23-2013, 05:09 PM   #1
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Lens ID in Exif data

My Kx does an Okay job with identifying Pentax DA & DA L lenses. However it does not recognize older Pentax or third party lenses. It even wrongly IDs my Sigma 24 -135 as a Pentax 16 mm. At least this info does not seem to show up in the EXIF data. Without this info, applying lens correction in post processing is a guess at best. I have a decent collection of lenses with lots of overlap in the 24 - 300 mm range. The focal length in EXEF is a clue, but not good enouth. Is there any way to identify the lens so the shots could be grouped for CA, and distortion adjustment? I do change lenses with the same subject as needed. Do the newer Pentax cameras do a better job with this? Any advice would be appreciated.

06-23-2013, 05:11 PM   #2
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QuoteOriginally posted by Pentax Bob Quote
My Kx does an Okay job with identifying Pentax DA & DA L lenses. However it does not recognize older Pentax or third party lenses. It even wrongly IDs my Sigma 24 -135 as a Pentax 16 mm. At least this info does not seem to show up in the EXIF data. Without this info, applying lens correction in post processing is a guess at best. I have a decent collection of lenses with lots of overlap in the 24 - 300 mm range. The focal length in EXEF is a clue, but not good enouth. Is there any way to identify the lens so the shots could be grouped for CA, and distortion adjustment? I do change lenses with the same subject as needed. Do the newer Pentax cameras do a better job with this? Any advice would be appreciated.
Many third-party lenses identify themselves ambiguously. It's not your camera's fault

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06-23-2013, 05:51 PM - 1 Like   #3
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As I understand the system, the lenses are hard encoded (the electrical connections on the base of the lens) and read by the body and written into the EXIF Meta Data of the image. Its the post processing utility software that actually interprets this information. So if the post processing utility does not have the full correct information nor the specific lens correction parameters setup, you are going to be in the situation that you are currently in. I would try as a test, a couple of the EXIF readers like PhotoMe where they both identify the lens and provide the binary information. The lens identification codes are out on the Internet, I have a link somewhere here (actually I think its on my other machine) where you can check and decode the lens ID yourself. Overall, I think that its more of a matter to have the post processing software vendor provide the correct and accurate lens tables, and correction/adjustment parameters. I think that users of the lenses that are not supported very well, need to gently "push" the vendors to update, maintain and enlarge their lens parameter/ID libraries.

From what I remember, Pentax does have some egg on their face since they do not support recording a focal length wider than 10mm, which introduces a problem with the Sigma 8-16 when its at 8 or 9mm focal length.

Then there are the older lenses, like the M42, K and M (along with remounted lenses like the older Contax/Zeiss). I would really like Pentax to enable the user to put identification strings (and their numerical tags) into the camera and then be able to select them. However, that would take updating the entire ecosystem of EXIF tags. I feel your pain since I have a Contax Zeiss 28/f2.8 and a Leica 28/2.8 that I swapped mounts on, along with a K 28/2.8 Shift. It makes identifying them sometimes difficult.


Last edited by interested_observer; 06-23-2013 at 06:12 PM.
06-24-2013, 08:52 AM   #4
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My K-x did a fair job, but I use very few auto lenses. It would properly ID my A 50, and the kit lens, those are the only ones I used.

With older manual lenses, it would only ID the focal length, and a standard line "K or M lens". This is because they don't have the electrical contacts to communicate with the camera.

I don't know about any others, but my K30 does not ID the lens at all, just the focal length. That's one of the few things I don't like about it...no lens ID at all, just focal length.

With my M42 lenses I could ID by the focal length. The 90-230 I would set to 250mm, the 80-200 to 200mm, and the 75-300 of course to 300mm. That would tell me what lens was used. The 50mm manuals were a different story, no way to tell. All I could do was make sure I only used one 50mm lens for the day then put all those shots into a folder, named for that lens. WIth the K30 the only way I can tell is that the A 50 will tell the camera what aperture I'm using, otherwise I have to do the same thing...make a note of what filename range was used with a particular lens. Otherwise it's a guessing game.

I usually just don't worry about it, if I intend to post a shot or 3 here I make a note of what lens was used so I can include it into a post, otherwise I just shoot and carry on...but I still do the same thing, I usually only use one 50mm lens on any given day so I don't have to sort it out later, I know what lens was used. Other lenses are no problem, I don't have many...One 200mm, one 135...well I do have another 135 but it's crap and I don't normally use it.

06-25-2013, 03:14 PM   #5
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QuoteOriginally posted by interested_observer Quote
From what I remember, Pentax does have some egg on their face since they do not support recording a focal length wider than 10mm
Only in the SR focal length maker tag. The EXIF focal length tag get correctly written as 8mm for my Samyang fisheye.
06-26-2013, 01:18 PM   #6
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QuoteOriginally posted by Paleo Pete Quote
My K-x did a fair job, but I use very few auto lenses. It would properly ID my A 50, and the kit lens, those are the only ones I used.
It will identify the kit lens, but not any A lens. The coding is stored in a chip in the lens, and Pentax started using this system only with the KAF mount, when they reserved one additional lens contact for serial digital communication.

With prime A lenses, the passive contacts do provide the focal length, but not the lens ID (with A zooms, this system doesn't help for getting the focal length).
06-27-2013, 10:23 AM   #7
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QuoteOriginally posted by RKKS08 Quote
It will identify the kit lens, but not any A lens. The coding is stored in a chip in the lens, and Pentax started using this system only with the KAF mount, when they reserved one additional lens contact for serial digital communication.

With prime A lenses, the passive contacts do provide the focal length, but not the lens ID (with A zooms, this system doesn't help for getting the focal length).
Correction.... With prime A lenses, the passive contacts do provide the aperture minimum-maximum range, but not the lens ID.
And the same should be true for A-series zooms.

A-series lenses do not communicate their focal length to the body. It will pop up a focal length question upon camera startup, remembering the last value entered. If you have changed to a different focal length, you have to manually change this value for SR to work properly. When it comes to an A-series zoom, there is some difference of opinion as to which focal length value the photographer should pick.
06-28-2013, 02:50 AM   #8
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@JimJohnson

Of course you are right; and I know it and experience it all the time.
It seems I was so fixated on correcting the assumption an A lens could be identified, my fingers acted by themselves.
Shouldn't happen.


Last edited by RKKS08; 06-28-2013 at 05:40 AM.
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