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Exif -- lens reporting incorrect data

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Dave2006 View Drop Down
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Post Options Post Options   Quote Dave2006 Quote  Post ReplyReply Direct Link To This Post Topic: Exif -- lens reporting incorrect data
    Posted: 05 May 2009 at 09:26
I have noticed that the exif data reads my Sigma 10-20 lens as a 28-80mm, has anybody else noticed this, is this a 'glitch' or a major problem. Any help or advice would be much appreciated.

Note this thread is an aggregation of three similar threads.


Edited by brettania - 04 July 2012 at 11:08
 



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Post Options Post Options   Quote pegelli Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2009 at 09:37
It's normal, my copy does exactly the same. This is because Sigma "reverse engineers" their chips the lens id is wrong. Exif will still give the correct focal length used in the right range from 10 to 20 mm.
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Post Options Post Options   Quote mhohner Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2009 at 09:40
What software are you using?

The EXIF data only contains a lens ID, and the reading software looks up the lens from the ID. Unfortunately Sigma does not play by the rules and uses lens IDs that were already used for other lenses. So reading software often picks the wrong lens name when reading a Sigma lens ID.

There are two solutions:

1. Make Sigma play by the rules and use truly unique lens IDs (unlikely), or
2. Reading software should cross-check other EXIF data, like focal length and aperture, to decide between lenses with non-unique lens IDs.
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Post Options Post Options   Quote pegelli Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2009 at 11:17
I read the lens with Sony IDC, probably just a look-uptable vs. the lensid, and obviously no 3rd party lenses in there (all my Tamrons are "unknown" and the Sigma's wrong). Lightroom doesn't read the lens id. Vivec posted a program that exactly does what you say Michael, see here. With that system you can see what lens you used in Lightroom, but I haven't tried it yet. However reactions from others who have are very positive.

Edited by pegelli - 05 May 2009 at 11:17
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Post Options Post Options   Quote Benoni Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2009 at 13:07
My Sigma 70-300 DG Macro reads as 75-300. Are Sigma just sloppy?
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Post Options Post Options   Quote Dave2006 Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2009 at 18:21
Thanks all for the advice, very much appreciated .........
 



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Post Options Post Options   Quote sybersitizen Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2009 at 18:29
Originally posted by Benoni Benoni wrote:

Are Sigma just sloppy?

Yeah.
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Post Options Post Options   Quote kampej Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2009 at 22:43
Strangely my Tokina ATX 80-400 reads as a 75-300, but my ancient (the original metal bodied version) Sigma 50mm f2.8 reads as "MACRO 50mm F2.8", perhaps Sigma were not so sloppy in the past!?
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Post Options Post Options   Quote pegelli Quote  Post ReplyReply Direct Link To This Post Posted: 06 May 2009 at 07:12
Originally posted by kampej kampej wrote:

perhaps Sigma were not so sloppy in the past!?


coincidence can cause a lot of things to happen
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Post Options Post Options   Quote Fuzzphoto Quote  Post ReplyReply Direct Link To This Post Posted: 06 May 2009 at 13:08
It's not that Sigma is sloppy, it's just that lend IDs are only supported for Minolta and Sony products.

And besides, lens ID is not exactly a standardized feature, not for the EXIF info, nor for image database software.
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Post Options Post Options   Quote Jozioau Quote  Post ReplyReply Direct Link To This Post Posted: 21 February 2012 at 22:39
This thread was started in 2009 so it's a problem that's been around for some time, and is still not fixed.
I recently purchased an as new Sigma 15mm f2.8 EX DG diagonal fisheye lens for use on my a900.
I post-process my images using Apple Aperture 3.2.2.
I noticed that in the EXIF data embedded in the images, the lens is mis-recognised as a Sony/Minolta 16mm f2.8 fisheye. It accordingly registers the focal length incorrectly as 16mm, despite it being 15mm. Aperture, shutter speed and ISO are all correct.
Having read this and related threads here on EXIF and Sigma lenses, it seems the problem is the way Sigma engineers its lenses so they are not distinctively identifiable and recognisable.
When I looked back at past images taken with my Sigma 10-20mm f4-5.6 EX DG on my a700, I also found that the lens in those EXIFs was mis-recognised as the Minolta 28-80mm f3.5-5.6 which is nowhere near similar, although in that case the focal length was correctly stated as 10mm through to 20mm, and aperture, shutter and ISO were all correct.
Probably not such a big deal, but a bit annoying, and of course misleading for anyone clicking onto images to get accurate EXIF data.
I have emailed Sigma tech support, but based on earlier entries in this thread, I'm not expecting any joy from them.
Joe
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Post Options Post Options   Quote Allan Olesen Quote  Post ReplyReply Direct Link To This Post Posted: 21 February 2012 at 23:01
Does Aperture support .xmp sidecar files?

If yes, you may want to try out Vivec's alphalensinfo tool, mentioned earlier in this thread.

This tool will use focal length and aperture from EXIF to try to find the most likely lens in a list of lenses sharing the same ID. That feature alone would probably solve your problem with the 15/16 mm mixup.

You can also edit the lens list and remove those lenses you don't own. That will make the identification even more reliable.
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Post Options Post Options   Quote Jozioau Quote  Post ReplyReply Direct Link To This Post Posted: 22 February 2012 at 01:58
I refer to a thread that started in 2009 in the Equipment Forums, Camera Talk, APSC DSLR section:http://www.dyxum.com/dforum/exif_topic46107_post994323.html#994323
However, I feel it more properly belongs here in the Lens Talk section so I'm placing my thoughts here. (If the mods don't agree, feel free to do what you think is best).

I recently purchased an as new Sigma 15mm f2.8 EX DG diagonal fisheye lens for use on my a900.
I post-process my images using Apple Aperture 3.2.2.
I noticed that in the EXIF data embedded in the images, the lens is mis-recognised as a Sony/Minolta 16mm f2.8 fisheye. It accordingly registers the focal length incorrectly as 16mm, despite it being 15mm. Aperture, shutter speed and ISO are all correct.
Having read this and related threads here on EXIF and Sigma lenses, it seems the problem is the way Sigma engineers its lenses so they are not distinctively identifiable and recognisable.
When I looked back at past images taken with my Sigma 10-20mm f4-5.6 EX DG on my a700, I also found that the lens in those EXIFs was mis-recognised as the Minolta 28-80mm f3.5-5.6 which is nowhere near similar, although in that case the focal length was correctly stated as 10mm through to 20mm, and aperture, shutter and ISO were all correct.
Probably not such a big deal, but a bit annoying, and of course misleading for anyone clicking onto images to get accurate EXIF data.
I have emailed Sigma tech support, but based on earlier entries in the original thread, I'm not expecting any joy from them.
Joe

Edited by Jozioau - 22 February 2012 at 02:06
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Post Options Post Options   Quote Fuzzphoto Quote  Post ReplyReply Direct Link To This Post Posted: 22 February 2012 at 11:58
Good Sir, what is your point?

The issue can't be solved. If a lens can't be recognized, it can't be recognized. AlphaLensInfo might work for most lenses, but not for all.
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