The computation is based on the FocalPlaneX/YResolution tags unless the FocalLengthIn35mmFormat tag exists already in which case it is used. See the Composite tag name documentation for a list of tags used in the calculation. (Also look up the tags used in calculating ScaleFactor35efl. Note that some of these are used only if others are not available.)

Maybe one needs a LR Plugin Interface for exiftool

Thanks, Josh

Send me a sample shot (of a blank wall, or better yet, something interesting ) and I’ll add it to the database. I use ExifTool in a number of my plugins, but limitations in Lightroom and in Windows make it somewhat of a heavy hammer. Macs come with Perl installed, but Windows doesn’t and never will, so I have to include a full Perl run-time environment in the plugin, which is both fragile and bloating. And frankly, it’s not all that popular of a plugin, so I’m reticent to spend much time on it when time spent elsewhere can benefit many. —Jeffrey

Just out of curiosity: are you using the FocalLengthIn35mm EXIF variable in any way? How do you compute the value, if not? Would it be possible to write back the computed value into the metadata of the image? I am messing with a couple of small cameras that do not provide the FocalLengthIn35mm and need to massage them using exiftool. Amazingly, it is possible to at least display that variable (using your metadata config tool: ‘com.adobe.focalLength35mm’), but it is not possible to sort on it or put it in a smart collection. I was wondering if your variable is related to it and how. And again, it would be very convenient if your plugin could write back the computed value into the image (or at least into the FocalLengthIn35mm variable in the database).

– Josh

Lightroom doesn’t give access to the FocalLengthIn35mm even if the image has it, so the plugin doesn’t use it. I compute it based upon the camera make/model and a large database of sensor sizes. It would be much better if I could use FocalLengthIn35mm directly, because that would take into account camera setups that don’t use the full sensor (e.g. the high-speed crop in some Nikons). The plugin keeps the data in its info.regex.lightroom.focallengthsort.FL35 field… I’ve updated my metadata-presets plugin to work with it… but I don’t know of any way to access it via a smart collection or the like. —Jeffrey

I use this plug-in and discovered that in some cases it displays a question mark (?) if the image does not have the FocalLengthIn35mmFormat label defined. Upon clicking on the ? line, the images that do not have that label are displayed (filtered). This is working as expected.

However in some cases there another entry “No Value” which is always at the bottom of the. Upon clicking that entry the line is highlighted but the filter is not engaged, the same set of pictures is displayed. Thus, I can not determine what metadata tag is involved.

This is not a big deal, but it is in all likelihood a bug that you might want to eliminate at some point.

Regards, Josh

I’m guessing that it’s a bug in LR2. Plugin custom metadata can be frustratingly iffy in LR2′s filter (try restarting LR, and it might work). Try it again in the real LR3 when it comes out and it should all work fine. —Jeffrey

Take a screenshot? —Jeffrey

This plugin is more than welcome. Works like a charm!

Thanx, Martin

No, sorry, LR doesn’t allow for it. —Jeffrey