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Capture One's Catalog size control #1
Ariel Glaze's picture
by Ariel Glaze
April 23, 2015 - 6:07pm

Is there any alternative to keeping the Capture One Catalog size in check?

So Capture one is great and all, but I’m noticing that its Catalog size is huge. Lightroom allows me to delete previews and maintain Catalog adjustments as instructions. Aperture 3 allowed me to delete previews to maintain the Aperture Library size more space friendly. I’ve tried shrinking the size of the previews, but that’s not what I prefer. Suggestions?

Richard's picture
by Richard
April 27, 2015 - 4:22pm

What do you mean by “huge”? If you aren’t importing images into it, then it’s mainly thumbnails and previews. 

Ariel Glaze's picture
by Ariel Glaze
April 27, 2015 - 5:45pm

I’ll give you an example. I imported 428 images as referenced files to both Lightroom and Capture One, no edits applied, both with previews sized at 1440 px.

Lightroom’s catalog is 5.8 MB, and its previews file is 193.7 MB.

Capture One’s catalog is 315.8 MB, previews are embedded inside the catalog file.

I can delete the Lightroom Previews file, but Lightroom also allows me to save space by getting rid of old previews. I don’t see a similar function in Capture One. Without this, Capture One’s catalogs, which are already bigger by design, get even bigger once adjustments start being applied.

Is there any function to get rid of old previews without losing my editing instructions within the catalog?

Richard's picture
by Richard
April 28, 2015 - 3:00am

The catalog is a Package, so it’s not an actual file. If you right click and choose Show Package Contents, you can then see the contents of it.

The Previews are in /Cache/Previews/.

Adjustments are in /Adjustments/.

The catalog itself is a file called *catalogname*.cocatalogdb.

You can delete files from /Cache/Previews if you like without causing any problems.


As an example of sizes. I have roughly 20K photos in my C1 catalog. 

The catalog package is 11.1GB in size. The .cocatalogdb file is 121MB, adjustments are 21MB, and the other 10.9GB  is previews and thumbnails. 

Richard's picture
by Richard
April 28, 2015 - 3:06am

I guess the question would be, and I know this is a big issue for some people because my father is obsessive about space on his hard drive (even though he’s only using about 10%, and likely won’t use much more than that in his lifetime), if space an issue with the size of the catalog itself, how long until it’s a problem with the photos themselves? The photos will take up much more space than the catalog that manages them.

Jon Kirshner's picture
by Jon Kirshner
April 28, 2015 - 4:20am

 According to Phase One Technical Support today, the Catalog (with referenced raw files) will approximate the Aperture Library. Note that the Aperture previews can be adjusted. According to Phase One, so can the thumbnails in their catalog. The adjustment is located in their ‘Preferences’. 

Mithel's picture
by Mithel
September 26, 2017 - 10:47pm

Richard, the catalog size example is very helpful.  Do you know what size you have set for previews?  Are you using the default size (2560)?  I’m thinking that even with a 4K monitor, I’ll probably decrease that to 2160 and still have full resolution at the full height of the monitor.  Probably we could go even smaller considering the menu bars eat up some space too.

Peter's picture
by Peter
October 29, 2018 - 4:35pm

The answer is, “yes.” There is a way to keep the catalog size in check.

I recently switched to Capture One from Adobe Lightroom. I already prefer Capture One in almost every way, but I had the same concern about the catalog file size. It not only takes up a ton of precious space on your system drive, it messes with syncing and backups. I have a 27” iMac. So reducing the dimensions of the preview images isn’t really an option. (I’m assuming you’re on a Mac, because I believe the preview cache is stored in a separate folder in the Windows version.)

So as another poster pointed out, the catalog file is actually a macOS package. You can take advantage of this to separate the cache directory from the database file, but there’s a trick to it. The following tutorial breaks it down into 10 easy steps to make Capture One store the preview images on an external drive (or any location of your choosing).…

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