TIP: How to Force the use of DNG sidecar files with Adobe Camera Raw
See my Leica SL wish list and Leica M wish list at B&H Photo.
Modification of orginal RAW files is in my view a risky game: files can be potentially be damaged, modified files are very large and have to be backed-up in their entirety, original shooting settings in the DNG are masked or overwritten. Basically, I prefer to think of my RAW files as original negatives/slides; I do not want them modified—ever. This has implications for forensics and law enforcement as well. Originals should be unaltered originals.
Unfortunately, at least in Photoshop, Adobe Camera Raw does not respect its own sidecar preferences: opening a DNG file modifies the file, writing/overwriting internal data as well as changing the file modification date. Each to his own, but I find this very annoying for backup, sorting by date, etc.
Solution: lock DNG files
The lockDNG and unlockDNG scripts are trivial. They lock or unlock all DNG files in the current directory, using the command line in Terminal. I save them as executable scripts in my PATH.
#!/bin/sh
# lockDNG ©2016 DIGLLOYD INC
# LOCK all DNG files in current directory, recursively
find . -name "*.DNG" -exec chflags -v uchg {} \;
#!/bin/sh
# unlockDNG ©2016 DIGLLOYD INC
# UNLOCK all DNG files in current directory, recursively
find . -name "*.DNG" -exec chflags -v nouchg {} \;
Using the lockDNG and unlockDNG commands is simple:
# type 'cd ' then drag desired folder into Terminal window. Example: diglloydMP:DIGLLOYD lloyd$ cd /Volumes/Archive/2016-0606-TripPhotos
diglloydMP:2016-0606-TripPhotos lloyd$ lockDNG
./LeicaSL/2016-0606-LeicaM240-WhiteMountains/L1000602.DNG
./LeicaSL/2016-0606-LeicaM240-WhiteMountains/L1000603.DNG
./LeicaSL/2016-0606-LeicaM240-WhiteMountains/L1000604.DNG ...
# Unlock DNG files diglloydMP:2016-0606-TripPhotos lloyd$ unlockDNG
./LeicaSL/2016-0606-LeicaM240-WhiteMountains/L1000597.DNG
./LeicaSL/2016-0606-LeicaM240-WhiteMountains/L1000599.DNG
./LeicaSL/2016-0606-LeicaM240-WhiteMountains/L1000600.DNG ...
When a DNG file is locked, this forces ACR to use sidecar files. It has some hassle factor: reorganizing/moving DNG files requires unlocking them. The OS X Finder shows lock icons once locked.