Sony A7 V Raw vs. DNG File Sizes

Forum|Forum|9 days ago
May 13, 2026
3 replies
43 views

I used DNG converter with Sony's three raw formats for the A7 V. Although the ARW files for the HQ and compressed formats are much smaller than the lossless compressed file, the DNG from the lossless compressed file is smaller than the other two. Does that make sense? Since the other two are lossy, I expected the corresponding DNGs to be smaller. Here are sizes for 3 shots of the same thing:

Lossless compressed: 48.56 MB ARW → 40.95 MB DNG

Compressed HQ: 34.05 MB ARW → 42.61 MB DNG

Compressed: 34.33 MB ARW → 42.87 MB DNG

Per Berntsen

Community Expert

I use the DNG converter with lossless compression for all my work.
For my Fuji GFX 50S camera, the file size varies between 46 and 62 MB.
The variation is caused by the nature of image content.
Images with predominantly smooth, flat, or out of focus areas compress better than images with lots of sharp, busy detail (or noise).
(The same principle applies to jpg compression, but with a much bigger difference in file size.)

I don’t use lossy compression at all, but it’s possible that a lossless compressed image with lots of smooth areas could have a smaller file size than a lossy compressed image with lots of sharp detail.

D Fosse

Community Expert

This made me curious, so I tried with my a7rV. I just let LrC do the conversion here; I don’t have the DNG converter installed.

All the DNGs are basically the same size, although the ARWs are very different:

The conclusion I draw from this, is that Sony’s compression algorithm is basically irrelevant to the DNG encoding. The original sensor data are extracted from the ARWs regardless of how it’s encoded, and then the DNG encoding follows its own compression algorithm.

I mostly use compressed lossless myself - not to save disk space, which I don’t care about, but to stretch the SD card capacity a little longer.

Small differences may just be the file header and metadata.

D

DaveJCummings

Community Expert

It could be just how things are being compressed. Is there any other info you could share?

G

glenn_cmAuthor

Participant

That could be. I’m not sure how much more I can add. My understanding is that all three raw formats are compressed, “lossless” is lossless (obviously), and the other two are lossy. HQ is better quality than “compressed”, though I found the files to be smaller and I saw the same mentioned in a book. I know the DNG format uses compression. That’s rather obvious, since it reduces the size of an already compressed raw file without any quality loss. It just surprised me that the smaller lossy raw files didn’t result in smaller DNG files, so my curiosity led me to post this to see if anyone knew why.

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