Lens model and lens specification

The lens model is the name of the lens as the camera reports it, stored in the EXIF LensModel tag (0xA434). It arrived with EXIF 2.3 in 2010, along with LensMake and LensInfo. Before that, the lens only existed in each vendor's maker notes.

All three live in the Exif IFD. The name format is up to the manufacturer: EF50mm f/1.2L USM from Canon, while iPhones put the camera module, its focal length and its aperture into LensModel.

LensInfo and the f/0 surprise

LensInfo is ExifTool's name for the spec's LensSpecification. Its four numbers are the shortest focal length, the longest one, the widest aperture at the short end and the widest at the long end. A prime repeats the same values. Zero means unknown, and Canon writes zeros for the aperture on some lenses, which ExifTool prints literally:

$ exiftool -G1 -s -LensMake -LensModel -LensInfo -LensType -LensID photo.jpg
[ExifIFD]       LensModel                       : EF50mm f/1.2L USM
[ExifIFD]       LensInfo                        : 50mm f/0
[Canon]         LensType                        : Canon EF 50mm f/1.2L USM
[Composite]     LensID                          : Canon EF 50mm f/1.2L USM
$ exiftool -G1 -s -n -LensInfo -LensType photo.jpg
[ExifIFD]       LensInfo                        : 50 50 0 0
[Canon]         LensType                        : 241

The camera, a Canon EOS RP, wrote no LensMake at all, and f/0 is just an empty slot.

LensID versus the stored lens model

Composite:LensID is computed by ExifTool: it looks up the maker-note LensType (241 above, also present in Canon CR2 files) in its own tables, using focal length and aperture to break ties. Sigma and Tamron lenses have often reported Canon LensType numbers, so LensID can confidently name a lens that was never on the camera. Trust LensModel first. Lenses without electronic contacts, such as adapted vintage glass, leave all of these tags empty or wrong.

Tagging a manual lens

The EXIF editor writes LensMake and LensModel in JPEG and TIFF, which is handy for tagging a manual lens; other tools are covered in how to edit photo metadata. LensInfo is not in our list, so use ExifTool:

exiftool -LensModel="Helios 44-2 58mm f/2" -LensInfo="58 58 2 2" photo.jpg