Guides

A complete guide to converting Canon CR3 files to Adobe DNG, and why it matters for long-term archives.

What is CR3?

CR3 is the next-generation Canon RAW format introduced with the EOS M50 (2018) and now standard across the EOS R line. It is built on the ISO Base Media File Format (the same MOV / MP4 container family) and uses Canon's proprietary CRX codec — a wavelet + adaptive Golomb-Rice scheme similar in spirit to JPEG 2000, with both lossless and "C-RAW" lossy modes. Compared with the older CR2, CR3 is smaller and faster to read, but compatibility is narrower: not every decoder has caught up with reverse-engineered CRX.

Why DNG

Archive compatibility

CRX is closed and proprietary. Future Canon updates may tweak its details, and older Lightroom or Camera Raw releases may not decode CR3 from a brand-new body. Once a CR3 is converted to DNG, it follows Adobe's openly-published 2004 standard and stays readable for decades.

File size

Converting CR3 to LJPEG-92 lossless DNG generally produces a file within ±5% of the original; sometimes smaller, because LJPEG-92 occasionally compresses certain Bayer patterns more efficiently than CRX-Lossless.

Editor consistency

Standardising the library on DNG removes "darktable can't open this brand-new EOS R5 Mark II CR3 but Lightroom can" headaches — every modern editor reads DNG.

Step by step

Open the RAW → DNG converter homepage
Drop a .CR3 into the dashed box, or click to pick
Wait for the status pill to turn READY (first visit downloads ~6 MB of .wasm; later visits use cache)
The detection line shows your camera ("Canon EOS R5", etc.)
Defaults — Lossless / Embed preview / Embed thumbnail — usually work; leave them on
Click "Convert"; the progress bar appears, and the browser auto-starts a download in 5–15 seconds

FAQ

"unsupported camera mode"

Canon occasionally introduces new sensor modes via firmware updates (pre-shoot, in-camera HDR composites). These may not yet be in the dnglab camera database. Submit a sample at the dnglab project; maintainers usually add support in the next release.

It's slow

The WASM build is single-threaded and rayon falls back to serial — expect 4–10× slower than the native dnglab CLI. For batch work, install native dnglab.

The DNG is larger than the CR3

Expected. LJPEG-92 is lossless and can't beat CRX-Lossy. If your CR3 is already lossless rather than C-RAW, the DNG will be very close in size.

What not to do

Don't delete the original CR3 right after conversion. Open the new DNG in Lightroom or darktable first; verify colour, white balance, and lens corrections look right. dnglab is high-quality but not bug-free; keep originals until you've validated the workflow.

Companion guide: Sony ARW to DNG. Full support list: Supported cameras.