Metadata
Two risks to weigh
Writing into the file keeps everything together: the description can’t be separated from the image. But every write modifies an original, and a failed write on an irreplaceable RAW is a permanent loss.
Writing alongside, in an .xmp sidecar, never touches the original. But the description becomes a second file, which can be lost, missed in a copy, or orphaned after a rename.
There’s no universal answer. There’s an answer per format.
The answer by format
Proprietary RAW (NEF, CR3, ARW, RAF…): sidecar. These are closed, publicly undocumented formats their makers don’t guarantee for rewriting. A third-party tool rewriting a NEF header takes a risk nothing justifies. It’s also what Lightroom does by default, for the same reason.
DNG: into the file. The format is open, documented, and designed to carry its metadata. A sidecar adds nothing but orphan risk.
TIFF and JPEG: into the file. Stable formats, writing well handled by every tool. The simplest case.
Derivatives and deliverables: into the file, always. An image leaving your studio must carry its author, rights, and caption within itself. A sidecar will never follow a JPEG sent by email.
The strategy that covers both risks
Serious collections don’t choose: they duplicate. Three locations for the same information, with different roles.
- The catalog is the working source. That’s where you enter, correct, and search.
- The file or its sidecar is the copy that travels. It guarantees the information survives losing the catalog.
- A plain inventory export — CSV or XML — is the copy that survives the software.
The consistency rule: the catalog writes to the other two, never the reverse without explicit arbitration. Otherwise two truths diverge and you no longer know which to believe.
The non-negotiable rule
Whatever you choose, insist on merging rather than overwriting. A sidecar or XMP block may hold fields written by another application. A tool that rewrites the whole file destroys them without warning — the most common cause of metadata loss when changing tools.
In practice
- Sidecar for proprietary RAW, internal writing for DNG, TIFF, JPEG.
- Always into the file for anything leaving your studio.
- Verify your tool merges rather than overwrites, before adopting it.
- Keep a plain inventory export as a third copy.
- Never rename an image without its sidecar in the same action.
Obscura Catalog only writes into an original on a choice confirmed every time, merges XMP sidecars while keeping the properties it doesn’t manage, and outputs the full inventory as flat CSV through its full export — the three copies stay consistent without one overwriting another.