Should I write XMP/ACR Files?

[iwaddo]

Lightroom Version Number

15.3.1

Operating System

1. macOS 26 Tahoe

I know this discussion comes up regularly so really sorry for bringing it up again.

Yesterday, one of the Lightroom Virtual Summit presenters was saying to turn the write XMP/ACR setting on. There was no explanation as to why, just 'you want to turn this setting on'. (unless you have a slow computer, in which case manually save the XMP/ACR after editing)

For me the XMP/ACR setting is off. I have left it turned off because

• Any image sharing is always with exported files, usually jpgs, so I do not need to send any XMP/ACR files with my originals
  • ... and I can create one on demand if needed
• I backup my catalog on exit from LrC most times and certainly if I've done any editing
• My catalog and the catalog backups are backed up to many places - two external drives and Backblaze

Up to now I was happy to leave the setting off based on the above.

Is my logic still sound?

Thank you for your help.

 

[iwaddo]

So I've watched a bit more of the video and the same presenter is telling people to drag images from the camera card to the folder the images will reside - the import will be from the new folder.

I thought the last thing you should do with images is drag (move) them from the camera card. Copy yes, move no!! What if the move fails?

For me the camera card is a backup. I do not reformat cards until I need them again, retaining the originals for as along as possible, just in case.

Maybe I should just ignore the XMP advice.

 

[Jim Wilde]

There are pros and cons to this question, but at the end of the day only YOU can answer it for you. The pros and cons are articulated in many places, and you will always get people who will dogmatically tell you to do what they do (be that turn the setting on or leave it off), so my advice to you is ignore the evangelists and decide for yourself. FWIW, I have that setting turned off but I do manually save metadata as part of my workflow.

Regarding the advice to drag the the images from the card to the folder on the HD, that would be a copy not a move, so not really dangerous. But again, depending on how you have your folders organised that could be superfluous advice, e.g. if like me you you a standard date-based folder scheme using one of LrC's standard templates then there would no need to manually create folder(s) before doing that drag from card into them, simply do a standard COPY import in LrC and have LrC create the correct date-based folders for you. Much more accurate and consistent.

 

[johnbeardy]

I don't see any weaknesses in what you are doing now, and little to be gained by following whatever this guy does.

Lightroom is meant to be an end-to-end app, from inserting the card through to export/print etc. Dragging and dropping in Finder is fiddly and more prone to errors, useful only if you want to deviate from LR's perfectly-good date-based approach.

For me the camera card is a backup. I do not reformat cards until I need them again, retaining the originals for as along as possible, just in case.

Remember the second copy in LR's Import dialog which is intended to provide this kind of short term backup, letting you free up the cards for re-use. A hard drive is probably less likely to vanish than a flash card is to disappear under some papers or whatever.

 

[clee01l]

I know this discussion comes up regularly so really sorry for bringing it up again.

Yesterday, one of the Lightroom Virtual Summit presenters was saying to turn the write XMP/ACR setting on. There was no explanation as to why, just 'you want to turn this setting on'. (unless you have a slow computer, in which case manually save the XMP/ACR after editing)

For me the XMP/ACR setting is off. I have left it turned off because

• Any image sharing is always with exported files, usually jpgs, so I do not need to send any XMP/ACR files with my originals
  • ... and I can create one on demand if needed
• I backup my catalog on exit from LrC most times and certainly if I've done any editing
• My catalog and the catalog backups are backed up to many places - two external drives and Backblaze

Up to now I was happy to leave the setting off based on the above.

Is my logic still sound?

Thank you for your help.

I think your logic is sound. With a good system backup in place and frequent Catalog backups, you will never need or use XMP/ACR sidecar files.

I do not understand why the Virtual Summit presenter made the statement without justifying it in some way.

 

[iwaddo]

I will be leaving the XMP write setting off. For now anyway.

I might now consider whether I should write XMP data as part of my workflow.

I always use LrC to import, copy, from the SD Card inserted into the reader in my Mac and make an automatic copy to an external drive. At this point I have three copies.

However, I have learnt something. I did not know that if you drag a file from a card to the Mac it copies, but if you drag a file between folders on the internal HD it moves. On the presentation the files had already been placed on the internal HD and they were pretending it was the SD card so when they dragged the images they moved, they showed the empty folder - hence my original question.

Thank you for your help.

 

[Jim Wilde]

However, I have learnt something. I did not know that if you drag a file from a card to the Mac it copies, but if you drag a file between folders on the internal HD it moves. On the presentation the files had already been placed on the internal HD and they were pretending it was the SD card so when they dragged the images they moved, they showed the empty folder - hence my original question.

I believe that the basic rule for drag and drop is that it will be a "move" operation if the source and destination are on the same drive, but it will be a "copy" operation when the source and destination are on different drives.

 

[iwaddo]

I believe that the basic rule for drag and drop is that it will be a "move" operation if the source and destination are on the same drive, but it will be a "copy" operation when the source and destination are on different drives.

Yes, to be honest I rarely drag and drop anywhere, instead I use command-c and option-command-v to move.

 

[Zenon]

Personally I find them clutter. I somehow accidentally enabled it on a new travel computer for a month. It took little work to get delete them. I back up my catalogue regularly and my OS is backed up to a dedicated ED using Time Machine. As a hobby shooter I don't really have much at stake so I don't worry about it.

I download files off my card to the desktop . From the desktop I pre-cull using another app. When done I import from the desktop but leave the folder there. My SSD is my fastest drive so I work from there. It also reminds me of what I'm working on, When done, using LrC, I drag that folder to a 2nd dedicated ED where I store my RAW files. I back that ED up to a 3rd dedicated ED daily using Carbon Copy Cloner.

So I'm pretty much covered and all the RAW files from the last shoot are on the card until I format it.

 

[iwaddo]

Personally I find them clutter. I somehow accidentally enabled it on a new travel computer for a month. It took little work to get delete them. I back up my catalogue regularly and my OS is backed up to a dedicated ED using Time Machine. As a hobby shooter I don't really have much at stake so I don't worry about it.

I download files off my card to the desktop . From the desktop I pre-cull using another app. When done I import from the desktop but leave the folder there. My SSD is my fastest drive so I work from there. It also reminds me of what I'm working on, When done, using LrC, I drag that folder to a 2nd dedicated ED where I store my RAW files. I back that ED up to a 3rd dedicated ED daily using Carbon Copy Cloner.

So I'm pretty much covered and all the RAW files from the last shoot are the card until I format it.

Thank you, this is helpful.

One thing I have started doing for larger shoots. Lots of high-speed similar images (birds) is importing to LrC but to a folder which I have excluded from the Time Machine and my overnight clone, they are still picked up by Backblaze and of course the originals are still on the card. I do not make import copies either.

I kept less than 50 images from a recent 2,200 image shoot and it just saves filling up my drives with images I've deleted. It is 1Gb not 40Gb.

Once culled I use LrC to move them into their place along with my other images where they are then backed up as normal.

 

[clee01l]

Personally I find them clutter.

I agree. I'd rather have my adjustments to all of my image files stored in one place (like a catalog file).

 

[Conrad Chavez]

Your logic is sound. As long as you back up the catalog one way or another (using the built-in backup feature or separate backup software), and you’ve tested and verified that a backed-up catalog successfully restores, you shouldn’t need to enable automatic sidecar writing. I don’t.

There have always been disadvantages to saving sidecar files by default, but it’s even worse than it used to be:

• Many more files to manage and back up.
• Possible performance slowdowns.
• Sidecar files don’t store catalog-level information such as membership in collections, publishing services, etc.
• The newest risk is: .acr files can be very large for images where pixels were generated, such as when Denoise or Reflection Removal are used. You’re duplicating synthesized pixels that were already added to the catalog’s .lrdata file. If this rate of storage consumption means you have to buy more storage sooner, that could cost you money given the recent steep increases in the price of storage.

I just did a test to see an example. I started with a 21.1 MB raw image with standard edits. Then I re-edited it with current features, and saved metadata files for each version.

Edits to 21.1 MB raw file	Size of .acr file / Size added to .lrdata file
None (Adobe defaults)	(No .acr file)
Traditional (Camera Standard profile, 3 masks, no AI)	0.98 MB (98KB)
AI Denoise	9.8 MB
Raw Details	14.4 MB
Reflections option of Remove tool	25 MB
Super Resolution	37.6 MB

So using the latest cool AI tools actually makes an .acr file that can be significantly larger than the raw file itself!

If someone frequently uses AI features, or worse, they often batch-apply AI features across entire shoots, then in addition to having a large .lrdata file, automatically writing sidecar files means creating .acr files that duplicate large amounts of the pixel data in the .lrdata file, causing free storage space to disappear at a much faster rate.

I do save sidecar files, but only rarely, just for the few raw images where I want the edits to be exchanged with other software, such as LRTimelapse, Adobe Camera Raw, Bridge, or After Effects. Then it’s useful and worth it.