11 Replies Latest reply on Aug 26, 2015 2:39 PM by CapeCodFrank

    How does LR identify the lens used to take a photo?

    CapeCodFrank

      Wondering if some one could tell me how LR identifies the lens that was used to take a photo?  I believe that the lens manufacturer supplies a LensID to the camera, which makes its was to the EXIF data.  What does LR do with the LensID?  I have a new lens (Tokina 11-16mm f2.8) which is being mis-identified.

        • 1. Re: How does LR identify the lens used to take a photo?
          THG_BO Level 3

          Hello,

           

          the manufature of the camera (e.gl canon, nikon) does not give uniq lensIDs to third party companies. Therefore these companies use old "unused" lensIDs for there lenses. A smart software (e.g. exiftool) can make a guess from the combination of f-stop, aperture and lensId which lens was used to take the image.

          In LR you have to choose the correct lens profile once and than you can set up this profile as default for this lens.

          LR_lens_004_20082015_233236.jpg

          • 2. Re: How does LR identify the lens used to take a photo?
            CapeCodFrank Level 1

            Thank you.  I understand how to choose the correct lens profile.  However, when I view the lens description, it says "20mm F2.8".  I want it to say "Tokina 11-16mm F2.8".  How can I make this happen?  Is there some table in LR which relates LensID 25791 with the description "20mm F2.8"?  Can I change that?  Is there an external EXIF editor which will allow me to change the EXIF data?

            • 3. Re: How does LR identify the lens used to take a photo?
              richardplondon Level 4

              One method is using this http://www.essl.de/wp/software/lenstagger-lightroom-plugin/ working from inside Lightroom.

               

              This allows data to be added or altered after the fact - the method only works on master copies and not on virtual copies IIRC. So you'd do it at the start of workflow, ideally.

               

              Sometimes the focal length can help identify the lens used - for example, on my Pentax dSLRs the shake reduction system prompts the user for a focal length, whenever you fit any lens which does not automatically communicate this info to the camera. That may be because of an adaptor, or it may be a legacy lens which lacks the internal electronics to do so (there are some wonderful older lenses to be found, at bargain prices, with which this is a fact of life). The chosen focal length then gets written into the image metadata. Once imported to LR, images can be selected accordingly and then LensTagger used to enter the desired lens description text. LensTagger allows a preset setup to be named and recalled.

               

              The reason it is necessary to do this via external metadata and exiftool, so far as I know, is that the SDK does not open up the Catalog lens description (nor whatever recognition table LR employs, to fill that in with readable text during import) to be modified directly.

              • 4. Re: How does LR identify the lens used to take a photo?
                CapeCodFrank Level 1

                Thank you very much, Richard.  I will check that out.  Looks like exactly what I am looking for.

                • 5. Re: How does LR identify the lens used to take a photo?
                  CapeCodFrank Level 1

                  Richard, I tried Lenstagger and am getting an Error 32512.  Do you know if the author still supports it?

                  • 6. Re: How does LR identify the lens used to take a photo?
                    richardplondon Level 4

                    I haven't used LensTagger for some time, and have no other source of information about it and its developer, than the website which I linked before.

                     

                    I don't know what your error code means, sorry. Is this a LR/LensTagger error, or an Exiftool error?

                     

                    I'd just comment here, that LensTagger AFAICT merely provides the convenient front-end, for a sequence of operations which could equally well be carried out by different means.

                     

                    Write LR metadata out to external file (so as to preserve all current image settings), alter that metadata externally to suit, then read LR metadata back in - for each photo concerned.

                     

                    For proprietary Raw there'll be a .xmp sidecar, which could be changed with a text editor, though Exiftool will also do this. For DNG or camera JPG you'd use Exiftool.

                     

                    You'd need to first identify and select which images need to change, inside LR (via whatever "wrong" lens info is seen initially). Then you'd write metadata out to file for those images (can't do this for virtual copies, remember) - say, at 10am. Outside LR, in your file browser you can see the modification date and times. Only if a file reported it was last changed at 10am today, would you modify that. Or you'd have some other to find these. Then back in LR, you still have those same images selected from before, ready to Read the selectively altered metadata back in.

                     

                    Exiftool can be set up to make a particular and repeatable change, by making a duplicate of the Exiftool program file, editing the filename to append some commandline options as below. You can (at least, in Windows) drag and drop selected files onto this program, or onto a shortcut to that program, using your file browser. Exiftool will run successively on each one, carrying out the stated operations, until finished. Backup data before trying this, and/or test thoroughly on sample images before using in anger - it's a destructive irreversible change to your precious image originals. Just the same as when LensTagger does it, of course.

                     

                    Such an edited filename might look something like this: exiftool (-Lens="Pentax A/24" -LensModel="Pentax SMC-A 24mm f/2.8" -FocalLength="24" -overwrite_original_in_place).exe

                    - and such data would be replacing whatever insufficient or wrong data LR has been able to infer from the camera provided ID.

                     

                    I have more than one lens which reports "A series lens" (appear non-unique), which is a strong reason one might want to do such a task. If it was merely an incorrect description (this happens a lot with Sigma) but nonetheless was unique "enough", that might still be acceptable to get the job done. Especially if other confirming info, such as focal length, is also available. I happen to keyword images with lens used (so that this is inherited readably in exports), and once that is done, I don't greatly care in practice about what the "official" LR lens info shows. Though I would certainly agree that it is much better and cleaner in principle, for this to be correct.

                     

                    regards, RP

                    • 7. Re: How does LR identify the lens used to take a photo?
                      trshaner Adobe Community Professional & MVP

                      CapeCodFrank wrote:

                       

                      Richard, I tried Lenstagger and am getting an Error 32512.  Do you know if the author still supports it?

                      Did you install ExifTool?

                      • 8. Re: How does LR identify the lens used to take a photo?
                        CapeCodFrank Level 1

                        Yes.  I am on a Mac (OS 10.10.5).  And typing "exiftool" into a Terminal window produces the exiftool documentation, so I think that part is working ok.

                        • 9. Re: How does LR identify the lens used to take a photo?
                          CapeCodFrank Level 1

                          Richard, thanks again for your detailed reply.  I only have one lens that is being mis-labeled in LR, so I think I will just live with it.  I will take your advice to just use a keyword to tag the pictures that were taken with my Tokina.  When I asked the question, I thought the answer was going to be simple, but I see that coming up with a work-around workflow is not trivial.  With the proliferation of manual and third-party lenses, I hope that one day LR will let users modify their system to provide custom lens data mapping.  However, I will not hold my breath.

                          • 10. Re: How does LR identify the lens used to take a photo?
                            richardplondon Level 4

                            Have you ever tried filter presets? You could make one which actually checks for the "wrong" lens description, but name this preset for the "right" lens description.

                            • 11. Re: How does LR identify the lens used to take a photo?
                              CapeCodFrank Level 1

                              I really am not having a problem with lens correction.  Adobe has supplied lens correction for the Tokina 11-16mm f2.8.  Once you select it manually, you can specify that that correction should be used as the default for the lens.  Seems to work.  I have stopped trying to fix the incorrect description.  This seems to be one of those things that appears simple on the surface but apparently is a can of worms.