Guides
This guide covers the characteristics of Sony ARW files and what to watch for when converting them to Adobe DNG.
What is ARW
ARW (Alpha RAW) is Sony's mainline RAW format, in use since the Alpha series in 2006 and continuing on the α7 / α7R / α9 / α1 / FX bodies. It is essentially an extension of TIFF, with one of the following compression modes:
- 14-bit Uncompressed — flagship bodies (α1, α7R V): largest files, fastest decode
- 14-bit Lossless Compressed — α7R V, α7 IV, α1, etc.: Sony's proprietary lossless
- 12-bit Lossy Compressed — older bodies' default: lossy at 12 bits per pixel
Why DNG
Some early Sony bodies (α7 II era) ship ARWs with colour quirks in certain RawTherapee and darktable releases. Conversion to DNG via dnglab applies its unified calibration matrices, producing colours close to Lightroom's defaults and making archives much easier.
For α7R bodies whose RAWs run 60 MB+, LJPEG-92 lossless DNG is often 10–20% smaller — meaningful storage savings at scale.
Step by step
- Open the homepage
- Drop the .ARW file (one at a time; for batches use the dnglab CLI)
- Wait for READY
- Defaults — Lossless / Embed preview — are fine
- Click "Convert"
- The browser auto-starts the download when ready
Approximate timings
| Body / file | ~ duration (M3 MacBook Pro / Chrome) |
|---|---|
| α7 III 24MP 12-bit lossy (~24 MB) | 2–4 s |
| α7 IV 33MP 14-bit lossless (~50 MB) | 6–10 s |
| α7R V 61MP 14-bit lossless (~120 MB) | 15–25 s |
| α1 50MP uncompressed (~100 MB) | 10–18 s |
FAQ
White balance differs from the native ARW
Expected. Sony stores white-balance parameters in proprietary SR2 / ARW metadata segments. dnglab reads them and writes them out as DNG-standard fields (AsShotNeutral / AsShotWhiteXY). Downstream editors should produce the same visual result, even if the internal values differ.
α7R high-resolution files run out of browser memory
Decoding a 61MP 14-bit lossless ARW transiently uses ~700 MB. If your browser crashes mid-conversion, switch to the desktop dnglab CLI.
Are HEIF / HIF files supported?
No. HIF is Sony's HEIF-encoded 8-bit format on α1, α7S III, and similar bodies — it's already a "delivered" format, not RAW, so converting to DNG makes no sense.
Related
Companion guide: Canon CR3 to DNG.