RAW + JPEG // How does LR recognise images that belong together?

[5omeone]

Dear LR community,

I have a Fuji XS-10 and take photos in RAW + JPEG. I have to re-import many of my images due to a service issue. I would like to know how Lightroom recognises that in addition to the

RAW there is also a corresponding JPEG, in order to allow a proper reimport. Does LR only considers the file name or are there other information?

Many thanks and best regards!

[JohanElzenga]

It also looks at the capture date/time as far as I know.

[John R Ellis]

Experimentation shows that LR just looks for pairs of files in the same folder, one raw and one JPEG with the same base name, ignoring the capture dates or other metadata.

[JohanElzenga]

Right! That means Lightroom will treat an unrelated jpeg as a sidecar if it just has the same name... Sloppy design!

[richardplondon]

Also the two files would need to be imported together (within the same import batch) I believe, to be considered as a Raw+JPG pair. An alternative could be to import only the Raw, and then leave the Catalog in ignorance about the presence of the JPG.

The effect would be the same so far as what the Catalog sees - except that the JPG file would in that case not automatically follow suit if this primarily Raw image was ever moved to a different folder, or else renamed, or deleted, from within LrC.

So far as what a "proper" reimport might consist of: there is some room for opinion there. Some people don't like seeing Raw+JPG, preferring to see the JPGs separately inside the Catalog. Others (and I include myself) prefer either Raw (only) or JPG (only), depending how the camera was set.

[JohanElzenga]

"Also the two files would need to be imported together (within the same import batch) I believe, to be considered as a Raw+JPG pair. An alternative could be to import only the Raw, and then leave the Catalog in ignorance about the presence of the JPG."

I don't think so. I think that 'Synchronize Folder' can also 'connect' new JPEGs as sidecar files to existing raw files. That is why I think it's sloppy that Lightroom does not verify the most logical thing: the capture date/time.

[John R Ellis]

"That is why I think it's sloppy that Lightroom does not verify the most logical thing: the capture date/time."

I believe that some cameras record separate capture times for raw/JPEG pairs. So even ignoring fractional seconds, it's possible that the raw records one capture time and the JPEG records that time plus or minus one second.

So LR would have to accept pairs that differ by a second.

[JohanElzenga]

"That is why I think it's sloppy that Lightroom does not verify the most logical thing: the capture date/time."

I believe that some cameras record separate capture times for raw/JPEG pairs. So even ignoring fractional seconds, it's possible that the raw records one capture time and the JPEG records that time plus or minus one second.

So LR would have to accept pairs that differ by a second.

By @John R Ellis

Interesting. I had never heard that, and I think it is odd because the raw and the jpeg are created from the same exposure, but if that is what can happen with some cameras then indeed Lightroom would need to use a tolerance of +/- 1 second.

[richardplondon]

True, Sync Folder does consider already-imported files together with whatever else it finds.

But "Import Photos and Videos" considers each import batch 'as new', watching only for any direct file conflicts. That was my point.

I'd agree that file-name alone can be a blunt tool, especially if one renames camera original files. I learnt to forgo doing so myself - which at least removes that complication.