Lossless compressed RAW
Lossless compressed RAW shrinks RAW files without discarding any data, so the decoded image is identical to uncompressed RAW but takes less space and time to move.
RAW files are big. Cameras offer ways to make them smaller: lossless compression, which packs the data more efficiently and restores it exactly, and lossy compression, which discards some data to save more space. Lossless compressed RAW is usually the best balance — smaller files with nothing lost.
Names vary: Canon's RAW and C-RAW, Nikon's lossless compressed and high-efficiency options, Sony's lossless compressed, compressed and uncompressed ARW, and Fujifilm's equivalents for RAF.
How it works
Lossless compression works like a zip file: patterns in the data are encoded compactly and decoded back to exactly the original values. Lossy RAW compression, by contrast, reduces precision in ways designed to be invisible in normal edits, though extreme shadow recovery can sometimes reveal it. Neither is the same as JPEG compression, which also bakes in processing. Decoding takes a little computing work, so some cameras shoot slightly slower bursts in certain modes — check your body.
An example: a day on one card
A photographer switches from uncompressed to lossless compressed RAW. Files shrink substantially, the same card holds far more frames, and offloading at the end of the day is quicker — with no difference in the edits.
RAW size and CloudTether
CloudTether delivers RAW files as the camera writes them, so smaller RAW files mean less to copy and less to upload. Over mobile data, though, even a compressed RAW is several times a JPEG, which is why live galleries and press work usually use JPEG only and leave RAW on the card, or send RAW later on Wi-Fi. If RAW must go live, choose the most compact format you're happy editing. See CR3, NEF and ARW for brand details.
Choosing a setting
Lossless compressed is a safe default. Choose lossy compressed RAW when space or speed matters more than the last bit of latitude, and test it on your own work first.
Tips and common mistakes
- Check whether your camera's burst rate changes with the RAW compression setting.
- Make sure your editor supports the format before a job — new codecs need updates.
- Send JPEGs live and RAW later when bandwidth is tight.
See also
Put it into practice
CloudTether tethers your camera to your phone and delivers every shot to the cloud, live as you shoot — no laptop.