For a manual lens (*Rokinon 8mm f/3.5 Fisheye) I want to add the focal length information to the EXIF metadata in the resulting pictures with
exiftool. I use the lens on a Canon 60D body.
Obviously I need to write the tag
For the Rokinon I set it to 8mm. Additionally based on my camera with an APS-C sensor I want to set the 35mm equivalent focal length as well. What is the right tag for this? One candidate I discovered is
However for another lens, the electronically connected Canon EF-S 15-85mm f/3.5-5.6 IS USM this tag is not set!!! The derived (composite) tag
FocalLength35efl is calculated, so the information must come from somewhere. According to details on the exiftool website it might come from
FocalPlaneXSize / FocalPlanYSize
For a manual lens, which tag should I write to reveal the 35mm equivalent info? So should I rather write
FocalLengthsufficient (and then FocalLengthIn35mmFormat will be calculated). I haven't experimented, but the question strongly implies that it isn't being written.
ScaleFactor35eflitself is calculated from the
FocalPlaneXResolutionet al tags.