Writing a different manufacturer LensModel into Exif?

[Alexiz]

Greetings everybody,

I've just started using ExifToolGUI (5.10), mainly hoping to add the missing manual lens info to the Exif of RAW files. Could Bogdan or somebody please explain whether what I'm trying to do is actually possible at all?

I am using a Sony NEX-7 camera with a manual Canon FD 135mm f/2 lens. In the metadata of RAW files that are produced, there is obviously no lens or focal length info, since they are not reported to the camera. Now, using ExifToolGUI, I manually write the "135.0 mm" value into the FocalLength tag; and I write the "FD135mm f/2" value into the LensModel tag. What happens next is that the FocalLength is correctly recognized in any program I open the file with; but there are problems with the lens info. Lightroom displays exactly what I added ("FD135mm f/2") in the "Lens" field of its database. But CaptureOne invariably displays "135mm f/1" (stripping "FD" and changing "f/2" to "f/1").

Is trying to write a Canon lens info into the Exif produced by a Sony camera a legit attempt at all? or this will never work correctly?

Thanks,
Alex

[Phil Harvey]

Hi Alex,

This is really more of a question for CaptureOne because the only problem is figuring out what metadata it displays for the lens.  ExifToolGUi can certainly write whatever is necessary.  But I can't help with what CaptureOne requires.

- Phil

[BogdanH]

Hi Alex,

What I assume is, that what you see in CaptureOne isn't value of LensModel tag. You can check that by changing FocalLength (and maybe FNumber) to some other value, while keeping LensModel as it is -after that you open the file in CaptureOne.
I did a quick look on phaseone homepage and couldn't find any info if CaptureOne supports/uses latest Exif specification. So, you better ask on forum there.

Bogdan

[Alexiz]

Phil, Bogdan -- thanks for clarifying. I just did the test that Bogdan suggested (changed the FocalLength and FNumber to a random value), and it appears that, indeed, CaptureOne displays something other than the value of LensModel tag. It seems it does take the first part of its "Lens" info from the FocalLength tag. (I changed the FocalLength to 100mm, and the Lens turned from "135mm f/1" to "100mm f/1"). Where it picks the "f/1" part from, however, is still not clear. Changing FNumber has no effect on this.

I guess, yes, CaptureOne's behavior is a bit odd then in this respect. (Certainly not worth going into manual tricks and all that just to please CaptureOne). Well, as long as at least Lightroom understands things right, I can live with that.

Once again, appreciate your explanation a lot.
Alex.

[BogdanH]

Another idea comes to mind... Try to write lens data into Xmp metadata, for example:
exiftool -Xmp-aux:Lens="Canon FD 135mm f/2"
-maybe it will be recognized by CaptureOne. Btw. this tag is also used in Adobe products (in case Exif:LensModel isn't defined).

Bogdan

[Alexiz]

Thanks for this tip! Just tried it -- but, no, didn't work. CaptureOne is stubborn. (It knows it's 100mm f/1 -- you won't fool it, with XMP or otherwise ;-)
Alex

[BogdanH]

...CaptureOne is stubborn. (It knows it's 100mm f/1 -- you won't fool it, with XMP or otherwise ;-)
Alex

What so you mean "it's 100mm"? -you've only mentioned 135mm.

Bogdan

[Phil Harvey]

I the previous post Alex set the FocalLength tag to 100mm, and CaptureOne is displaying this in the lens name now.

- Phil

[BogdanH]

Uh.. thank you for clarifying, Phil.

Bogdan

[Alexiz]

Yes, that's what I meant, sorry for the confusion. CaptureOne's "Lens" name appears to be a composite field which, as I've figured, basically displays [FocalLength]+[MaxApertureValue]. So, if I go to Exif and set FocalLength to 135mm and MaxApertureValue to 2.0, then CaptureOne says the lens used is "135mm f/2". (I still don't know where to put "Canon FD", so that it get inserted in front of the "135mm f/2" -- I guess nowhere, since CaptureOne probably extracts that info from MakerNotes).

I suspect CaptureOne behaves this way (i.e. compiles the lens name from FocalLength + MaxApertureValue) only in the absence of proper lens info specified in MakerNotes. Should I use a RAW file generated by a Canon camera with a Canon lens, CaptureOne will correctly display the full lens name (e.g., "EF50mm f/1.4 USM"). I've just checked this Canon file in ExifToolGUI and see that CaptureOne must be taking that lens name ("EF50mm f/1.4 USM") not as a composite kind of thing but indeed from the LensModel tag -- however, not from the one in Exif, but from the one in MakerNotes (since, even if I delete LensModel in Exif, the lens name is still displayed correctly).

Alex