Sometimes we want to know what lens was used to shoot a particular scene. Lenses are recognized by the lens-ID in EXIF metadata and a combination of factors (recorded also as tags in EXIF), such as: minimal focal length, maximal focal length, maximal aperture at minimal focal length, maximal aperture at maximal focal length, lens mount, lens format, taking focal length, maximal aperture at taking focal length, taking aperture, and so on. This information is also used by photo software applications to offer better information and possibly better processing of your photos.
The reason I bring up this topic is that I encountered an issue for my Tamron, SP 90mm F2.8 Macro lens whose EXIF lens-ID is 25811. From various forums I found that this ID is used for the following lenses:
- Minolta,AF100mm F2.8 Macro (D)
- Minolta,AF 100 F2.8 Macro RS
- Minolta,AF 100 F2.8 Macro
- Sigma,105 F2.8 EX DG Macro
- Sigma,105 F2.8 EX Macro
- Sigma,AF180mm F5.6 Macro
- Tamron,SP 90mm F2.8 Macro
Interesting enough, most of my photo apps I use identified this lens as “AF100mm F2.8 Macro(D), TAMRON 90mm F2.8 Macro, SIGMA 90mm F2.8 Macro or SIGMA 180mm F5.6 Macro”, an indication the use the EXIFTOOL library.
The EXIF lens-ID information is written by the camera, photo apps just displays what the camera has written in the ‘Lens ID’ field. Most photo apps, with the exception of some special EXIF editors, don’t allow end users to edit the lens-ID field. However, some photo apps are able to make some lens correction by using other clues besides the EXIF Lens ID to tell one lens from another. Since I don’t do much, if any photo corrections, this mis-identification is not a problem for me. However, if you do use lens corrections features within your post-processing, be aware that a wrong lens identification can cause a problem.